Vue is not a framework, at least not in it's simplest form - drop in UI library.
I agree that Vue does much more than Intercooler and in theory, it could be seen as an overkill. But in reality, a developer will probably use it in conjunction with jQuery and then he might be better off replacing these two with Vue.js
I mean, regardless of anecdotal specific usage, vue is a framework. And a nice one too! Just entirely too much for something that can be fulfilled by a simple pjax tool
I agree that Vue does much more than Intercooler and in theory, it could be seen as an overkill. But in reality, a developer will probably use it in conjunction with jQuery and then he might be better off replacing these two with Vue.js