That's pretty much true of all news groups, isn't it. The amount of accumulated knowledge being lost because Google Groups works so poorly is saddening.
Back in the 90's comp.sys.mac.* (comp.sys.mac.misc, comp.sys.mac.system, comp.sys.mac.wanted, comp.sys.mac.hardware, etc.) was extremely active. Web fora either didn't exist or were just getting started and that's where everyone exchanged information, went for help, and bought and sold stuff. Strangely, all the selling was done on comp.sys.mac.wanted, not on comp.sys.mac.forsale.
There's some great stuff back there, if you can get Google Groups to give it up.