Therefore, all the complexity of building interfaces will be in the libraries and because opinions on such complex issues vary, there are many libraries to do the same thing.
Eventually the interior ones are recognized and culled. They typically are supported for quite some time after becoming uncool, it's just that no one wants to work with lame, obsolete tehnology for good reasons.
The solution I see to this are compile-to-JS languages that make it possible to use a different ecosystem of libraries than te JS one, like Scala.js. However, those tools are also still evolving, so one way or another you're dealing with a lot of library churn in frontend development right now, so learn to pick winners and stick to them until it's as weird to use them as jquery for complex UI was in 2012.