Web components work very well in isolation, and/or within a homogenous web component framework/library.

However, it is still pretty challenging to pass data throughout web components (in a way that allows you to build a complete application). HTML attributes are not great for data transfer (string serialization for everything). JS properties are a bit opaque (not represented by markup). And everyone ends up wanting some sort of property binding system, which may be unrealistic to standardize.

I think there will always be a place for some amount of framework/library support necessary for application builders.