It's very important to remember that Facebook's standardized UI played some role in making it successful. I don't think it would be as successful were it as customizable as MySpace.
If you define it as effectively destroying non-techy interaction with the wider web & customization then yes it has been a resounding success.
Just like 99% of people want cars with an automatic transmission and take it to the mechanic for any issues, 99% of people just want a tool that gets out of their way and lets them achieve the goal. Whether it's driving to their destination or seeing photos or video calling their friends/family.
If you asked my parents, their goal never was to create anything on the internet, or browse niche websites and learn their layouts. They're not going to learn it in their advanced years, and perhaps they would rather spend their time on other interests they have such as gardening, cooking, etc.
But success isn’t necessarily a good thing. I’d say Facebook has had an extraordinarily negative influence on the world regardless of its success.
Also 99% absolutely do not want an automatic vehicle, I’m assuming you live in the US but it’s not at all like that anywhere else.
https://www.edmunds.com/fuel-economy/five-myths-about-stick-...