"It's the universally expected turn 4 play when facing Green." - Satisfied?
Sure
Or even just, 'better be prepared for a t4 moss when facing green.'
So tell me.. how does one prepare for a turn 4 moss? You can't prepare for it in your mulligans bc you don't know you're playing green until the first turn.
I think you need to be careful not to run decks that are overly greedy on their mana bases. I think you need to make sure your deck has sufficient land. Or, I think you need to be aggressive enough that t4 wasted means death. Most of those decks are going to be "try hard" decks. But then again so are decks running 4x Moss in ramp shells. If you expect to beat a "try hard" deck consistently, you need to be playing a "try hard" deck as well. Within "try hard" decks there are plenty of answers to t4 moss. Control has more counters than ramp has moss, and those counters come online t3. RDW probably doesn't care if you kill one of its lands. Even crats - which is probably tier 2 - can draw through the tempo loss, when built correctly. Jund Sac steal gets hurt hard, but it's in a good position in the later game, so t4 moss hurts it, but I think it's still generally favored in the matchup. I could go on, but I feel like that's enough.
Now let's be clear about something - the only decks that
are likely to be able to even have a chance to survive t4, t5 moss are aggro decks. But I assume that doesn't come up often. I'd bet your Rakdos deck would crush t4 moss, most of the time (e.g.: it's prepared).
You also need to realize that while t4 Moss often wins games, t8 Moss topdeck can often lose the game for them instead. It's a gamble. It's a good gamble, but it's a gamble.
edit: also, come on beast... you know this stuff already.