It is not without a cost, the cost being an lack of standard ways to accomplish things. For long running projects where devs may come and go, having a standard way to do things is an incredible advantage, and will result in a much more consistent code base.
For real world front end project, this is a much more important concern, imho, than ease of picking up. For your particular use case, I agree something like Vue is a better fit.
I've seen people do write-up of how they re-write the front-end from jQuery to Angular|Ember|React so it's not like there are many long-running JS projects that require solid structure. 3 years old (small-medium size) projects tend to get re-written.
Here's another one that I've seen and experienced before: 10 years old product where some section of the products are written in pure JS, some section in jQuery, some section in BackboneJS + Marionnete, some section using EmberJS.
Disclaimer? I don't use Vue, but I've seen this argument made for Ember (against Angular 1.x) and Angular 2 (against React).
Simply because one has to learn the standards in the former case. In the latter, it is mostly left to the users imagination and their own sensibilities, which differ from person to person.