As a counter-example look at Sencha, who have long alienated developers using their ExtJS toolkit, and this has deepened since the takeover by Idera.
I think it's great for enterprise form-fill-in applications. It's a complete widget set for doing in the browser what GUI apps from 20 years ago had in Java (for example)
I have no interest whatsoever in writing web applications by using multiple components from multiple sources. I want to use a single toolkit. ExtJS satisfies my requirements. The tooling is awkward, but I've learned how to use it.
examples
"web desktop" https://docs.sencha.com/extjs/4.2.1/extjs-build/examples/des...
widget library (classic) https://docs.sencha.com/extjs/4.2.1/extjs-build/examples/bui...
Please shout (email in profile) if you need any help. Good luck!