I think that at the very least 1 type of feed should come from outside gardening. Several types of feed should be available from crafting (Culinarian and Alchemist maybe), and others should come from gathering.

Making all feeds come from gardening seems like a ridiculous bottleneck. Hopefully, they actually meant that you can get chocobo feed from gardening but neglected to refer that you can also get it from other sources. The rank cap remover being a gardening only item I'm ok with. These will sell for a lot, but ultimately, the need for them won't be as great as with the other feeds once you reach rank 20 on your choco.