It’s simpler, there is a client for everything even mobile phones, it has a move command, it has props that can be edited without a copy command, pagination is however you set it up to be rather than a one size fits all approach, it can be just as scalable as S3 if you build it to be, it has much simpler locks that make them easier to use so you might actually use them, keys can be longer than 1024 characters, actual directories exist.
That’s just the protocol level. The biggest benefit for me isn’t really at the protocol level, but part of the design of my own WebDAV server: deduplication. I can throw the same file into my server with 50 different keys, and it will only take up the space of one copy on disk. This basically moved the logic of deduplication from my application to the blob store. Mountains easier from an application design perspective.
There are use cases where S3 is better, but they are few and far between. And, WebDAV is extensible. You can build whatever functionality you need into it, rather than using some proprietary protocol.
That’s the thing though, free social media was giving them massive returns. But the line must go up. And once they completely saturated the market, there are only two ways to make the line go up: expand the market (give Internet to communities that didn’t have it), or extract more money from your existing users (enshittify). Facebook made a half assed attempt at the first one for a couple years, then pivoted hard to the second.