They want to force you go green for that effect. They don't want the colorless options to be more efficient than the colored ones here. We've seen Bant control decks recently play Farseek specifically to ramp into Supreme Verdict, so their goal is working
2cc Rock into a 4cc Wrath has been a traditional play in a number of previous standard formats.
A) If my memory is correct those lists ALL had 4 Thragtusk in them right? That's my point, the deck would never have run Green just for Farseek but because it also had some Green cards (main or side) that it actually wanted to cast. If there was no Thragtusk incentive, they wouldn't have played Farseek even if the later was the more important of the cards - adding the third color wouldn't be worth it if you could get that investment back (which Thragtusk really helps to do).
Furthermore, Farseek fixes better than any mana rock in a format with shocklands. Lotus Cobra in a format with fetchlands isn't going to be outdone by any mana rock either. Elves and Birds are preferable to mana rocks in any deck that can take advantage of the increased creature count. Sylvan Caryatid has been seeing less play recently but it can still block like a champ - something a man rock can never do. Cards like Cultivate and Kodama's Reach are card advantage cards straight up (even if they are slower rampers). Like if 2 CMC mana rocks are better than the absolute worst of Green ramp cards, I can't really shed a tear - the best Green ramp cards aren't going to pushed out of any format by halfway decent mana rocks.
I'm also just really fucking tired of seeing 3 CMC mana rocks. I don't want to play them in limited, they are almost all worthless on constructed, I don't want to put them in any of my casual decks or Cubes, etc. The cards are worthless and take space and make me want to go on John Olivier-esque rants whenever I see them. Here's how to design a mana rock that I will actually give a shit about:
Dragon's Rock (2)
Uncommon
Dragon's Rock ETB
Tap: Add one colorless mana to your mana pool
Tap: Add one mana of any color to your mana pool. Use this only to cast Dragon spells and activate abilities of Dragons.
You'd obviously have to test it with the midrange/control decks in mind in FFL (as opposed to just throw it into current Standard willy nilly) but at least it would be a card I'd be interested that could contribute to an fun/interesting standard as long as they were designing with card in mind from the start.
B) Oh I thought you meant current standard as opposed to just Magic's history. My bad. Sure, yeah that was a thing.