Well yeah, except I kinda figured it out before I got older, though. Concrete, granite, clay, round, trapezoidal, open baffle and a bunch of different wave guide shapes and everything else they have tried over the years. I just saw a lot more of it revisited via the diy route, and a tendency for many to throw every over-the-top woodworking trick at projects as well.
Just 'my' personal experience though. Not to say others can't find interest in such things but it seems super redundant to me, personally. The other topic that resurfaces repeatedly once content becomes thin for seemingly all 'content creators,' at some point is, the magic cable discussion. I know the perpetuator knows better, but will bring it up because it causes a lot of hits rather suddenly. Just seems kind of desperate, this far along in the game.
Perhaps it's just me, but new information on most audio forums across the net seems to be drying up as well. At one point, a few years ago, this site, for example, was pretty busy every day. Now when I stop by some evenings, there are one or two users online, when there used to be 30 or more somewhat regularly. Now I see topics at the top of the sub forums up for days, with the last response a week old. This tells me that most of the exciting things have been used up.