"Each server, being privately owned, can follow their own criteria for rejecting content as they please and users are free to choose what to read and from where."
Doesn't this same line of thinking apply to the Internet as a whole? Couldn't your question of "Why would anyone use Nostr?" equally be asked for "Why would anyone use a web browser?"
A web browser is a viewing portal to a specific page, accessed upon request
A relay is a stream of stuff you then have to filter
It's really like apples and oranges, web pages or blog sites is probably a better thing to ask about than web browsers
a specific page is also stream of stuff you then have to filter
if I bend over backwards far enough, sure, I can see how it can look like that
A relay is more like page updates across all of the internet being event streamed