I love ExtJs. In my opinion, their framework and backward compatibility is something other frameworks should strive to achieve. Currently, React, Vue, Svelte etc. are still at what I consider to be at ExtJs 3 level, where each component was defined in a single file. I wish they would open source their framework and really only on support subscriptions rather than the ridiculous license that they have, although I think that ship has long sailed. I just wish there was something even somewhat close to ExtJs in the open source world. Sadly, hardly any front end developers are even aware of it.
It has been a long time since I looked at it, but (price aside) I seem to recall not being too interested in it because the actually complicated components (tables and such) had too many design and functionality constraints.
Partly, this was due to designers living in their own dream worlds prior to development, partly to functionality limitations.
When you have a green field to play in, buying into Extjs felt like sitting in a tiny pen, even if the grass was very nice.
