Then how would you know about all the interesting stuff you’re missing out on in FB marketplace?

I'm sure I am, but my point was at least locally, Craigslist is still quite active, and not apparently stagnating.

If it hasn’t grown by 10x over the last decade as all of the population got online with smartphones, it’s stagnating. It might still be active with the same OG users, but it missed the new market and that’s squarely in the “stagnant” category.