Gulfstream enables pilots who wouldn't be able to otherwise cut it to buy their way into an airline job. Getting to 1500TT and successfully interviewing is tough and a lot of people can't do it.

It isn't anything to do with Gulfstream's training itself, its that it (and other places like it) allow those on the lower end of the scale to slip through the cracks and become qualified enough to get into an airliner. Not to say there aren't some exceptional pilots that came through Gulfstream, but it also enables those without the natural skill/ability/drive/etc to become a successful airline pilot the chance at being one anyways.