The card is clearly powerful, but has some glaring limitations
However...this is only three times as much mana as we could have gotten by using any other animated artifact or enchantment with Hanna, Ship's Navigator (since any of them can be sacced to Phyrexian Altar)...and probably less mana than we would get out of bouncing and recasting Doubling Season (assuming there are multiple Minion Reflectors in play, once we get to the second trigger we will most likely be putting much, much more than triple the permanents into the battlefield)
A Brimaz, King of Oreskos proxy lets you run this powerful staple across every deck you own without paying secondary market prices
Were talking about the classic, pixel-perfect nostalgia of the Kanto region right up to the wild, Terastallized battlefields of modern Paldea
Technically, the first new card type was called mana source, but that was just an experiment to make producing mana not cause problems in gameplay