Ron's assessment is pretty spot-on, unfortunately. But there is hope for would-be sponge keepers, IF they give enough priority to their care.
First, I must admit to a similar lack of success with them. I have had limited success with hitchhiker sponges that came in on live rock. They have survived and grown for two plus years.
This brings me to the first of a few key points. I have read many articles on sponges, and one thing they all said was that the sponge must come to you still attached to its rock. None of the sponges I have purchased online have come that way, and all have perished. Since none of the dealers seem to understand or care, in my opinion, the best way to get viable sponges is to buy live rock with sponges attached. It's not an ideal solution, admittedly. Ideally, you'd collect your own, with rock attached.
Sponges feed on dissolved organic carbon (DOC) and possibly the smallest of phytoplankton, nannochloropsis. Most aquariums generally have ten times the DOC of natural seawater, so food is not really a problem. However, there is one nutrient that is lacking in most aquariums - silicate. Silicate is a building block component of sponge skeletal structures, like calcium is for corals. Most folks avoid it because it tends to cause diatom blooms. Snails also need it to build their shells. A lack of silicates is probably the reason some have small sponges that hang on for years, but never really grow much. The fix? Dose sodium silicate. I ordered some from an online chemical store-easy. After dosing, I get a small bloom on my front glass. I easily clean it with a magnet cleaner, and the water borne diatoms are taken up by the sponges. If you want sponges to grow, give them silicate!
The last piece of the puzzle is placement and orientation. Unless they are the photosynthetic variety, sponges need shade. Most of us bathe our tanks in wall-to-wall light. Put a sponge in bright light and it will be covered in algae in days. This clogs the pores and the sponge starves. Carve out a nice shady spot for sponges to prevent this. Sponges need current in order to feed, so current is critical. Finally, orientation is also important. Look for the excurrent syphons, which are the bigger holes on sponges. Orient the sponge so that the big holes are on the downstream side of the sponge. This way they can work with the current, rather than against it.
That's about it. Sponges are a real challenge, especially in this era of super hi-tech tanks, where the water is stripped of life. I think more would have success, if we just made their ideal conditions a higher priority. I have never seen a dedicated sponge tank. I do think I have pretty close to ideal conditions in my lo-tech tank, so I still hope to put it all together, one of these days…