Only if you go after run of the mill coding jobs after your phd, in which case why bother at all. When applying for a postdoc, you'll very much want to bury that part of your work.

Plenty of high-paying quantitative jobs requires such a degree and experience. The majority of phd’s don’t go on to support their family with a tenure-track academic salary.

Or you could be applying for a HPC research job in one of the countless non-university setting that also does that sort of thing. Then having both a relevant PhD and some relevant hands on experience will be extremely helpful.

Why would you rewrite something that works well instead of just linking to it?

Because you need to modify or extend it in some nontrivial way.