Except making employers do only easy things will make them stagnate. People who do nothing but simple CRUD apps over and over won't even be particularly good at making CRUD apps... whereas the guy who builds an Unicode font renderer in his free time always seems to write better code for some reason.

Getting better at your job is not just a "personal want" but very much something that the employer appreciates aswell.

Of course reinventing the wheel isn't good in corporate because the reinvented wheel is buggier than the ready made npm package but employers should go out of their way to find hard problems to solve that they can pass to their employees. It's called a growth opportunity.

You can’t convince an employer with that attitude. They’re gonna keep exploiting their employees and “encourage” them to do their “personal development” in their free time.

Unless you work for enterprise consulting where employers appreciate replaceable cogs that they randomly drop into any project, and nicely out project budget regardless of delivery quality.