I'd probably describe that as "bad behavior" as you hire people believing they'll focus on improving things inside the company, inside of focusing on padding their CV. Of course, wouldn't be bad if it's both, but selecting the latter in front of the other seems non-optimal for the employer.
If you go through enough people like that, you end up with a ball of software spaghetti that anyone working on will struggle with, instead of a polished architecture ready to nimbly be changed when needed.