It's better if libraries don't just assume jQuery is everywhere, because I suspect those days are ending. Apps built on newer front-end frameworks like Angular and React might not need it, for example.
As a library author it's becoming more important to think case-by-case -- use raw JS if you just have some simple selections or XHRs, or use Zepto/etc if that covers you, and only depend on jQuery if you really need its richness in your lib.
If it's just a general library to use anywhere, then sure build it with no dependencies.
But if it's a library intended for Angular then the library would be built with Angular as a dependency, much like it would be with jQuery.
I don't see a negative with a library being built that has dependencies if it is intended to be used in conjunction with the thing it is depending upon, since in most likelihood a like-minded developer is already using it.
As a library author it's becoming more important to think case-by-case -- use raw JS if you just have some simple selections or XHRs, or use Zepto/etc if that covers you, and only depend on jQuery if you really need its richness in your lib.
So in that spirit, I appreciated the article.