You probably won't like this but it's your attitude that's the problem. Change it. You assume you are infallible and smacks of sanctimoniousness. Now, you are entitled to such feelings if the clients were some finance suits with no idea of tech, but by your own admission they are not only engineers but also former devs. Just engage in the discussion, who knows there might be solutions lurking there if you take off your shades and earplugs.
getting 10 pm to 6 am sleep, some things are that simple, life in general is much much better, for one I hardly get irritated about small things like I used to.
Two things happened simultaneously. The forum aficionados were 90s kids who entered middle age around 2010s and sort of weaned away from online engagement, and the new gen had other shiny venues to socialize to begin with. Further, the older folk when they came back for online engagement adopted the new venues. Not everything is cannibalization by evil big tech.