I think this is one of those simple questions where the answer is a lot more complex than it appears on the surface !
My feeling is that the sign-up process is a lot harder than on centralised social media. On (say) Facebook, you basically give them a name, an email address and create a password and your account is open. No messing around with keys, wallets, or any of that stuff. But on centralised social media, you're then encouraged (strongly !) to "create a profile" which means giving away lots of personal information - Hive doesn't have any of that.
Legacy social media tends to be a lot more intuitive and have better "Help" screens - one of the advantages of having centrally managed well-funded development teams. But by being developed by the community, Hive ends up with lots of fascinating dapps and a lot more depth than the legacy social media platforms.
Hive doesn't have a single "figurehead" CEO who can do the rounds on TV or other social media. Nor does Hive have a PR department who can turn up on call anytime a journalist wants an interview. My view is that this may slow us down because the legacy news media don't have someone to talk to, but the upside is that we're not linked to an eccentric billionaire's ego.
Legacy social media puts a huge amount of effort into being as addictive as possible. Hive isn't as pushy, doesn't bombard users with retention emails or try to trick people into being active - it's the responsibility of each individual user to decide how much activity they want to do. It may not work so well for user retention, but the users we keep are staying because they want to, not because they feel guilt-tripped into it.
With Hive, most users need to invest at least a little bit of cash to get started. The legacy platforms don't, because the user IS the product.
Having said all that, I feel that Hive does need to do more to avoid unnecessary complexity and to better explain how it works and what all the Dapps do. But it's relatively early days, and I feel strongly that this is a case where quality is better than quantity.