The quality however is meh.
Libraries are a very touchy subject. Most of the time, outsiders to the field just want "plug and play".
Professionals in the field? Holy fucking hell can we get neurotic. In a large company you may have more than one person dedicated just to managing libraries and drawing them to your standards instead of letting the internet do it. And there's a whole list of reasons why one may do it vs. not do so. (Schematics are a form of design expression and as such there are many standards and thoughts on optimal forms of expression, including dependency on the particular sub-industry you are)
No different than software engineers having their favorite programming language, markup language, config file language, code style guidelines, deployment workflows, etc.