Another way of looking at the "magical" number of minimum hours for any given job is that it's a tool to reduce the number of applications the HR team have to read through. Until this winter (and shortly before COVID hit and nullified all zero-experience job opportunities), a certain European LCC required a minimum of 300 hours for a NTR cadet. Why? Do you reckon it was because an extra 100 hours of SEP (because nobody will trust you with flying their MEP with a fresh CPL these days) would have made you a far better A320 pilot? I don't think so. First, it was quite likely an attempt to significantly cull the number of applications so that the HR team don't spend their entire time scrolling through thousands of applications of 200-hour guys and girls. Second, it was perhaps one extra hurdle to test the motivation of the cadets, i.e. is the candidate serious enough to find some way to do 100 extra hours?
There has always been a huge oversupply of applicants at the very bottom of the experience ladder - and that's precisely why getting that proverbial first job was no easy feat for the vast majority of pilots. The higher up the ladder you climb, the less equivalent-or-better competitors you have. That's largely why there are often those hour requirements - because the company wants to try and hear from the best candidates first. If no suitable person is found among those, the minimum requirement goes down. The exception to this are airlines with a long-term career orientation and highly consistent training philosophy. They are often the ones who dedicate a certain percentage of their vacancies to cadets because they want to work with people who were trained their way and have been working up to their standards from early on in their careers.