New technologies arise so quickly that it is hard to achieve mastery in one before it is made obsolete.
So Knockout, Backbone, Angular, Aurelia?
And Azure released several new services into Preview in this month, while several that had been in preview were moved to General Availability. I can barely keep up with reading about the new services, let alone conduct experiments with the new features.
It has never been more true that if you are hiring purely to find someone who matches your checklist of technologies in use, you are missing something. As an experienced hiring manager, I suggest that candidates for advanced positions need experience in the core technology, and some version of front end/back end or whatever.
But you want people who are willing and able to learn new things. Their history is merely an indication of their aptitude and attitude.
Developers naturally get attached to technologies they’ve invested in. There is no good rule for when to stay with something and when to move on.
This is a fun field for someone who loves learning and relishes change. But it can be exhausting. And at some point, we must adopt a strategy to survive or we will all become shepherds and beekeepers.