Yes. On many levels.
Largely due, over the last 10 or so years, manufactures making more and more kits with high-end features at mid-range prices.
Drums like Gretsch Calatina and Renown lines, Mapex Armory, 101 variations of Pearl and Tama, Yamaha Tour, PDP, etc, etc flooded the market with nice drums that don't cost an arm and leg.
And then there are the 101 smaller manufactures that have popped up over the last 10-20 years, making good quality drums.
And the big manufacturers keep coming up with new variations. The last NAMM show I was at 2 years ago, Pearl had easily double the number of lines it had back when I worked for a top Pearl dealer. At the DW booth, some of the DW (non-collector lines) and PDP stuff was so close in the description, I had to ask what the difference is, and I still am not sure. And the list goes on.
In general, one can buy a mid-line kit now that would be on par of a high-end kit from 30 years ago.
So, as these increased choices hit the new market, they even eventually hit the used market.
Now, if you want a decent quality drum kit, you have so many choices.
And then it comes into, why pay $3000 for a top-end kit when a $1500 kit is close? And why pay $1500 when a used version can be had for $900?
And if you can get a used 1/2 way decent kit for $900, the demand for the used $3000 kit goes down.
Sure, there will always be exceptions for certain rare/vintage kits.
But so much very nice stuff is widely available.
And then, as mentioned, Ebay used to be the only game in town and was largely just individual sellers. Now ebay has a ton of competition, and many sellers on such sites are more than just a person trying to sell something out of their garage.
I don't look at used kits very often, but when I do, I'm surprised to see some of the same sets still for sale months or years later.