A better way to nerf armorers (experimental villager rebalance)

As someone who has wanted armorer villagers to be nerfed for quite some time now, I am disappointed with the implementation in the experiments. The new system is illogical and not accommodating to every player's environment. If a world is either exhausted of or lacking diamonds entirely, then the player is out of luck. Furthermore, making diamonds part of the cost of gear defeats the purpose of trading in the first place. Not only is it now nonrenewable, but with the buffed diamond generation, having mined diamonds at all means that you likely have enough to craft gear anyway.

The solution, then, is to make the diamond-to-emerald trade (which, previously, was at the level right before unlocking diamond gear, and now is master level in taigas for some reason) a trade that the player must complete a given number of times to level the villager up. For example, giving 12-18 diamonds to an armorer would unlock the diamond gear trades, which would then only cost emeralds.

This may be implemented by increasing the threshold for leveling up by a lot, and by increasing the xp earned from the diamond trade appropriately. This way, the player still needs to spend diamonds to obtain diamond gear, but the armor is still renewable and cheap, and those without access to diamonds can still get the gear, just with a lot more effort to level the villager up. Furthermore, if the diamond trade was buffed (1 diamond for 15 emeralds), it would give another use for diamonds in the late game.