That was my experience as well. I recall groups occasionally finding or being allowed to buy things like a wand of CLW (almost always found as loot or part of quest payment). I think that there was only one game that I participated in where the CRPG style waterfall of CLW wands & that was a very strange group including one player with a d20 modern PC & a second with a literal shadowrun PC beside some 3.5 PCs while 4e was new.Most groups I saw played 3.5 like 2E.
As late as 2014 I saw groups who weren't playing like what you're describing. Eg they weren't using wands of CLW. Mist groups only had core book maybe one or 2 more Randoms.
Ours was the only group even vaguely plugged in. There's a current group still playing 3.5 they allow phb+1.
I think a big reason 4E died was most groups were not playing online meta so 3.5 worked for them.
Druid was an exception. Least popular Class though. I saw a grand total of 2. One was OP other was fine.
Also I didn't find THAC0 all that "confusing" as a middle schooler. I don't see one for ad&d2e, but it looks like the red box basic set of the age had an "ages 10 & up" on it... Perhaps falling on different sides of that line explains the differing experience with grok'ing THAC0.