@Gofrit
I like the idea of tying higher tiers to quests and/or exploration. This would make it easy for guilds to progress while also giving solo players an opportunity. This is a personal tangent, but one of my favorite activities as a solo player is sneaking into areas I shouldn't be able to handle, such as when I managed to gather a wagon full of azurite despite not being able to beat any Jotun 1 on 1.
In that sense, we could get rid of recipes altogether and require you to discover new ways to craft gear in the world, beyond primitive and maybe tier 1.