it only hurts fish, so, with no fish, no harm.
another risk is pouring back in the change water too fast and stirring up a bunch of waste in the sandbed. that can be addressed by pouring slow, across the upper rock tips and letting it go back in smoothly. the only two params that need to be matched are temp and salinity.
when fish are in play, as was El Fab's tank, smaller changes can be done so they have room to swim in. he did 50% for three years, so, to test theories on whether or not large water changes are dangerous if done right you have to know these details:
-who has documented longer success using less changes?
-if he did 50% weekly, that means his corals were hanging in the air for a while until he refilled. Would it make sense that an 85% change would have killed his tank? If not, why would a 100% (were it not for the fish)
Fish in pico reefs shorten their lifespan. Fab wasn't going to get much more out of that tank as is, it crashed due to cyano which could not be beaten when he disturbed the tank and tried to move it. Going that long, on partial changes, put the tank on the edge of the cliff of no return, and since pico reefs are always prone to little unpredicted insults if you stock yours accordingly, expect a quicker death unless you have the same abilities he does.
it comes down to whether or not you want to follow the masses and get a short term reef, or follow the narrow path and get a long term one. Most people want fish, low water change work, and the 3 gallon pico will allow that for several months. That is the typical lifespan anyway so its no big deal to run a tank like that.
The only reason to do large water changes and use no to low fish loading, along with massive coral loading so the tank looks cool, is if you want a true long term tank. Short term tanks are ok, most people get bored with them at 25 mos anyway, then the algae will just give the keeper another reason to start over in another tank (using the same short term methods interestingly)
such is the circle of tanks on web forums. temporaries
here is another perspective...consider our big thread in the nanos forum where we correct all the tanks following the common pathway...pico reef pest algae problem challenge thread. see how many of those were smaller pico and nano tanks, ran with partial water changes and high bioloading.
They present to us in that thread only when near death, never as preventative. Can you imagine your tank turning out differently by month 18? The reason I offer care methods the way I do, is to save you from ever having to become part of a 60 page thread about why the publics view on how to run a pico reef is flawed endlessly.