It isn’t like puppy mills came along after the 1500 hour rule either, they’ve been a thing for decades. Much prior to the 2000’s you just couldn’t reliably get interviews much below something like 1500tt/300 multi, and the real number was often higher. Now if the point is that the schools & CFI’s are milking students for hours by not soloing them when they’re ready, well there could be a lot of reasons for that, some more charitable than others. Might also be that this 737 CA is seeing the sort of pilots that used to be only hired at the regionals, he’s just used to more airline experience than he’s getting, or maybe he’s just so salty cows wanna lick him. In any event, if you’re a 121 captain, it’s expected that you’ll be doing some instruction, regardless of what you’re flying and for who, all part of the job.