Don't be so sure people aren't going elsewhere. Besides craigslist, there's also the not-Internet option, which I think many of us on here forget, possibly largely because it's so seemingly difficult to measure (in our skewed experience).

I've met many young people who still default to pen-and-paper for things like note-taking. It's tempting to dismiss them as luddites, but I can't exactly blame them, given how much I know about just how user-hostile modern computer software and hardware can be.

I agree, but the providers are financially incentivized to make the UX worse via all this stuff, which reduces the number of providers offering a non-terribled UX.

In becoming ad revenue maximizers, taking for-granted assumptions on audience, this situation doesn't optimize for serving the audience well. And since their models are to provide content in bulk, it keeps users served "well enough" to keep coming back, as opposed to less-funded alternatives which might provide a better UX, but don't provide the bulk content that monied sites can.

Fundamentally, people visit sites and endure bad UX if the content is there to draw them. The utility cost of bad UX often isn't the dominating factor.