Isn't it the other way around?
One of the major flaws is the lack of consistency between clients and UX.
#nostr is a protocol, but no app provides experience and functionality worth attracting an audience not limited to nerds and weirdos. Also, the lack of control over your content is not significant, and there is no proper way to prevent bots, spammers, or anyone to stop interacting with you.
Still a long road ahead.