> Our memory is limited too,
Is that really true, though? I mean, there most probably is some theoretical limit how much data can fit in a structure of particular shape composed of particular number of neurons, but are we really hitting that limit? Are we even capable of hitting this limit after a lifetime of learning and experiencing? It may feel that way, but it could be a side-effect of some focus-switching and memory-compressing heuristics implemented by the brain.
What I mean is that there are obviously people who learned both JS and a framework, so why wouldn't anyone be able to do this? And I can guarantee that, once you learn it, both JS and a framework fit in your 'cache' perfectly. Actually, I felt no difference between recalling things before I learned a framework and after.
In other words, learning a new framework should be possible for anyone. And programmers are expected to continuously learn new things anyway, it's not "added" cost, it's just part of the job. From this point of view, I can't see any problems with introducing a library, given that it's a good library (docs, active maintainers, community, etc.)