Tu Ku; I think you may still be missing the point. To over-simplify things, only pure water evaporates, so no "bad stuff" is exported during evaporation.
Many people are happy with water changes as a method of nutrient export. After all, what goes in (nutrient import/feeding), must come out (nutrient export/water changes). This however, isn't your only option, as there are more efficient methods of reducing and exporting "bad stuff".
Your first line of defense is assuring that you are not importing too much "stuff". This can be accomplished by rinsing frozen foods well, selection of "cleaner" foods, having a TDS reading of 0 with your source (top-off) water, and having a salt mix that has the right "stuff" in it.
The last one may be a hard one to fulfill, as recent studies have proven that salt mixes are not truly representative of natural sea water. Excess trace elements (heavy metals) often come from the water change itself. For this reason alone, water changes may be counterproductive in some cases.
There are many methods of nutrient export. I elect to use as many as possible, according to cost effectiveness and convenience. Water changes rank poorly in both of these categories, so I limit water changes to the amount of water that the protein skimmer removes and salt creep.
Some more efficient methods of nutrient export and reduction (assimilation & dissimilation) are protein skimming, the growth of macro algae & benthic invertebrates, ozonation, ultraviolet sterilization, molecular absorption (carbon, ion exchange resins, polymeric absorbents), livestock selection (xenia, snails, clams etc.), biological filtration (including deep sand beds) and mechanical filtration (cartridges, pads, manual removal). Any of these options will outperform water changes if properly executed.
If you have a problematic tank, poor husbandry practices, and/or don't properly implement the above methods, then water changes are quite necessary.
My experience has proven (to me) that even if the source water has a TDS of 0, and the salt mix is optimal, the reduction of nitrate and phosphate etc. is only marginal and fleeting with water changes.
If you change 10% of your water, then the "bad stuff" will be reduced by only 10%. Once phosphate is removed from the water, more bound phosphate will leach from calcareous media (calcium based rock and sand). Within hours, your original phosphate level returns, negating the water change efforts. Nitrate takes a little longer to return, but it will be back before the week is up in most cases.
You can counter this process by changing more water, but by the time your export catches up with the import, you're chasing your tail. You're better off focusing your resources on more cost effective technology and methodology.
The problem with water changes, is they act only as a bandaid. Excess "stuff" is a symptom of a poorly balanced system. I'm not saying that a perfect balance is an easy accomplishment, but a higher order ecosystem approach, with the right equipment and good husbandry practices will keep your hands out of the tank.
There is no evidence that marine aquariums have a deficit of trace elements, in fact the opposite is true. Water changes offer no significant "replenishment" aspect. Calcium reactors function very well in this role with very little operating cost or maintenance.
The most successful aquariums you will find, base their success on the delicate balance of livestock, not on the equipment or husbandry. The best equipment in the world won't help a system with poorly selected livestock. Invertebrates are capable of reducing any compound that accumulates in a reef aquarium. Some invertebrates like xenia can be harvested for profit and nutrient export.
There are many "natural" aquariums that rely solely on livestock for filtration, with only artificial lighting and pumps for water movement. Many aquarists have solved serious algae and pest problems through the addition or deletion of fish or invertebrates.
The simple addition of a sand sifting goby or cucumber can make a night and day difference in the cleanliness of the substrate. I've read many posts where the author has bent over backwards, doing daily water changes to solve this same problem, to no avail.
Chemical mishaps can be cleaned up through the use of binding or oxidizing chemicals like sodium thiosulphate or potassium permanganate, or through chemical filtration (carbon etc.). No need to stay up all night doing water changes, only to remove some of the offending chemical or medication.
Water changes have their time and place. Nano tanks function very well with major water changes because the cost and convenience is favorable. A 75%-100% weekly water change will save you the expense and space of a protein skimmer, chemical dosing, ozone, UV, refugia, benthic invertebrate culture, calcium reactor and a DSB. All you need is a pump, some carbon, and a bucket for the water changes. This model doesn't work for a large tank, as a 75%-100% water change isn't feasible.
There are some merits to water changes with aquariums up to 50 gallons as well. A couple of buckets can be changed without shocking the inhabitants or killing the coraline algae, due to UV exposure. The loss of coraline algae alone defeats the possible benefits of a water change. Coraline algae out-competes nuisance algae for nutrients and real estate. Turning the lights off during maintenance will eliminate the issue, but it introduces new visibility problems.
The efficient execution of water changes isn't an easy task. You have to match all of the water parameters, including PH and temperature, which takes time and space to achieve. most hobbyists, myself included, don't have the resources to store that much water or the patience to remove and add it in a non-injurious fashion.
As the saying goes, "if it ain't broke, don't fix it". Everyone is looking for something different from their aquarium. If you have a few fish and some undemanding corals, then obsessing over your (nitrate, phosphate, silicate, magnesium, calcium, Kh etc.) levels is counterproductive. If you have an interest in hard to keep SPS corals that require exacting lighting and water parameters, then you need to do a little more work, but it's a labor of love.
If you're enjoying your aquarium as it is, and there are no measurable differences with regular water changes executed, then you've answered your own question. If you want to increase your bioload, limit the number of times you have to wipe the glass, or increase coral growth and color, then try some of the other practices before resorting to water changes.
