About the 'island' comment, you should compare island to wastes. When we see a land with 'tap to add UUU. Use this mana only to cast instant or sorcery spells' it will make sense. Mishra's workshop has made a lot of cards get restricted so that it doesn't need to, and that's a pretty loud fact.
I hate this logic so much. I thought we were over the "Workshop is Black Lotus" argument. Artifact mana is way more restrictive than that and makes deckbuilding for it very eschewed. A "Black Lotus land" would've been restricted ages ago since if wouldn't have any deckbuilding constraints at all. They're 2 entirely different things.