While the card sees play as a two or three-off in control decks, thats about the extent to which it sees play
Just that turn, but that's great to lead or support decks that use combat lots, just like the color he's in
That's probably why WotC leaned towards Treasure: Gold allows you to double-dip in case some other effect requires you to tap permanents (because you can tap your Gold to pay for that other effect, and then still sacrifice the Gold for mana in the same turn)
How Do Dual Lands Work in MTG
Unfortunately, this causes a lot of confusion, since the term "proxy" has been a part of Magic for a long time and the use of proxies is widely accepted for certain purposes and types of play
Assuming you take advantage of having access to every card in MTG, theres no reason why you shouldnt be pulling out obnoxious card after obnoxious card here