It seems the ExtJS community has fallen off a bit as the company has (in my opinion) put it in the rear-view as they focus on Sencha and mobile. I also never really felt that I have seen what a true ExtJS app could be. The examples are the same as they were 5 years ago. Only the theme has been changed. You get a lot for free with the datagrid and charts but they aren't the only game in town for this.
No one wanted to build customer facing ExtJS apps because of performance issues, hard to style so that it doesn't look like some dull enterprise thing and at the time Rails was just getting popular. I havn't touched ExtJS in a while but building an admin CRUD in Rails would be much easier. The extra features of ExtJS can be gotten elsewhere and easily integrated.
Angular just seems like a breath of fresh air when comparing it to ExtJS, and again most of the components can be found elsewhere.