It definitely boils down to personal preference in the end. I always hated trying to wrap my head around solutions before understanding the problem.

By using Flask first, you also end up thinking "wow, every time I build a flask app I go through these same repetitive steps. Would be nice if they were automated". Then you find they are automated in Django.

If you learn the solution first, it seems irritating and sometimes you never understand the problem that it's solving.