For a new player to fully gear up in rank 10ish gear, they are looking at spending 150k gil. This isn't reasonable as it takes like 2 hours and 5 leves to get to rank 10.

EDIT:

If gear was restricted by level then people would be forced to create/recycle/buy lower level gear. Thus drastically dropping the price of lower level gear, making it easier/ more fun for new players.