Scotty, because the Top 14 (like everything else in the world) is all about money. To some extent it's about winning, but in the end coaches and players are pressured by the sort of money that goes into the whole industry. Presidents aren't paying tons of money for the wellbeing of France's talent or whatever, they're businessmen. Some of them might have a few principles, but that's nothing in itself. Money rules, money commands, and money dictates what happens.
If all that matters is winning Scotty, then what do you want for your team ? The best coach, best wingers, best flankers...etc money can buy. There's a salary cap, a limit ? Okay, let's make it so we fit what the law on the paper says, but in reality we're hiding stuff. Like asking an alcoholic "did you drink beer today ?!" and he answers "no" and pretends like all is well but he had another kind of drink, just not beer. He didn't lie really, but he's not saying the truth either. There are all kinds of ways around rules and laws...
So if Toulouse have Hosea Gear or Yoann Huget on the wing, we'll get Habana. They don't give a shhit about French talent and France and French Rugby or whatever, once you're in that whirling spiral, it sucks everything in, and if you want to compete in this league you're going to have to put the best team money can buy together, which sounds logical. But it's a lot easier and way faster to get the best, already trained and more talented anyways than the local French guys; than going through the time, effort and wait for the young guys to grow.
Of course there is a quota as we've said. Every team needs to have at least 55% of Frenchmen. But in Toulon's case, they sit a lot of the French guys on the bench and play their Lobbes and their Wilkinsons.
The league can only go in this direction, although there'll always be French talent about, obviously.