ExtJS was way ahead of its time - while it was most famous for its grid component, the data package, tooling ecosystem (long before we had node) and component architecture was amazing. Its learning curve was tough, but it was so worth it when you got to grips with it.
Jack’s post acknowledges what most of the community felt for years - the biggest mistake was alienating the developer community while trying to chase commercial success. The irony is that ExtJS and Sencha could have been hugely successful commercially if they had approached it differently. Instead the only people building on it were usually people working in large corporations, and even those would never use it for hobby projects outside of work due to minimum purchase of multiple seats to use the non GPL license.
I look back fondly on my time using ExtJS as a developer. They had some of the smartest engineers around working on the framework, a great community in spite of Sencha’s best efforts and I learned a metric ton along the way. Who knows where it would be today if it all went a little differently!
