First of all, leadership is a powerful feat that must be allowed by a GM into the game. Player-DM One on one time is pretty much essential. The rules are somewhat indistinct (but clearer than many areas of the game) and rightly so. However, that means that the question you ask is entirely campaign dependant.
This is how I would run the feat in terms of consequence:
1) Stay-at-home cohorts don't earn XP; what was once an awesome 5th level cohort at 7th level is now an annoyingly inadequate draw on resources at 9th: you must clothe, feed, and house him, as well as paying for his equipment etc, if he gets to keep anything; a cohort who is unfulfilled might ask for pay.
2) A cohort has to want to follow the PC. Calculate the leadership score for maximum level; apply any relevant negative modifiers, and perhaps apply some others. (Cohort or followers are commanded to work without pay -2, Cohort has not spoken to PC within 7 days -1, Cohort has opposed alignment -1, etc) Eventually an unhappy cohort might just lose interest in the PC or prioritize some other cause; especially if the new leadership score is no longer high enough to support a cohort of that level. This is not punishment for player action. This is consequence of character action. You can't abuse people and expect them to like it.
3) The PC would have to attract a new cohort (taking months or years to do so considering the rarity of an all-crafting wizard of appropriate level and alignment; maybe a 1% chance per week? DM: "Still no wizards at all, but these fighters want to join your cause, and they think you're just great!") The process could become great campaign fodder. The wider the PC sets his scope, the easier it will be to attract a follower of his alignment.
On the other hand, cohorts that go adventuring are continuously filled with good things to say about their leaders; they participate in the action so they get XP (at a reduced rate, but enough to keep them current): that is, I think, the intended use, to have someone who follows you into battle and to help change the tide of history. Leadership could be called "Sidekick + Friends"...
As for the whole "Pyramid Scheme" thing, that's how pathfinder deals with building a kingdom. This is how you get thousands of followers, and form a town. It's awesome when you do get the chain going; there is always a strong support network for the party and at that rate there are bound to be a few all-crafty types, or some crafters with the cooperative crafting feat. The competitions to have the highest leadership scores are often amusing. PCs trying to convince their followers of their DM-arbitrated "special powers" etc.
But that's my campaign...