A binder cannot get infinite healing without spending a resource. In order to get the infinite healing, you need to bind Buer. At the level that Buer first becomes available, you can only have one vestige at a time, and Buer does basically nothing besides healing. So you're spending a very big resource: The entirety of your primary class feature. If you want to be able to heal, then you cannot do anything other than healing, all day. Even the Healer doesn't have it that bad. At higher levels, you can get multiple vestiges at once, but you still top out at only four, and spending a quarter of your class features on healing is still a mighty high price to pay.