Maybe in the case of Twitter it makes sense (I'm not using Twitter myself), but in general, as the OP notes, the UX is worse with PWAs than it is with native apps. So, to rephrase your comment to reflect this

> Why would I use the app, when I can get /something worse but workable/ out of the PWA and not have to download a hundred meg update every week

And then the answer might be --- because your phone has 128 gigs of memory, your home wi-fi has unlimited bandwidth, and the updates all get downloaded automatically while you're sleeping, you might decide to go for the better UX in exchange for nothing at all.

Or just use Tweeetbot, it weighs in at 7.2MB and the last update was 8 months ago.

Every time I load the page for a tweet in their PWA on iOS it gives me an error, and then I reload the page and it works fine.

Why would I use the Twitter website, when I can get the same out of the app, it loads faster, and it actually works consistently? Plus I don't have to log in in app webviews all the time.

Downloading a PWA isn’t smaller and it also needs updates just like a native app. And the answer to your question is the comment you replied to.