nuzeIt's really not that difficult if you were to teach people from the ground up, but the problem is that playing that style has a few very important differences to the current meta. There are a lot of habits that players of today's meta have that are in direct conflict with how the epsilon style works, and it becomes very hard to break those habits unless you have open minded adaptable players.
When we first started practicing for GA, there were many times where in stalemates we would get a pick, and papi would take the initiative to go and sac for the medic, but losing a player there is the opposite of what should happen in the aggressive playstyle, but it's become the norm so that's what people instinctively do (a big gripe I have with today's meta is it devalues the lives of flank classes). It took a while and some minor disagreements before we actually started making headway - a massive reason that it actually worked was that I was calling with 5 gamers that all had great attitudes and were willing to try something new, but that is not a common team structure.
Edit: I'd also say the reason I tend to call it the froyo style is that, despite epsilon being great at pushing every small advantage, froyo is more directly applicable because they do it with the demo being a low heal supportive role, whereas epsilon had the demo as the high heal carry role - this is ridiculously hard to do properly at a top prem/invite level after all the nerfs/buffs unless you have termo dm
Unfortunately epsi/froyo style has obvious and objective drawbacks :
-it does not help you to get the pick(s) you need in the first place. Against teams that don't make mistakes you're still pinned
-According to sigma's momentum guide and considering equal skill between two teams, it's not possible to make team pushes (=commit at least 4 players) consistently off one pick that is not demo or medic without the forward spawns advantage;
-the style is completely random when facing snipers; consider an area like process or badlands mid or snakewater 2nd; it's not possible to go in while avoiding a sniper completely and you have no way of knowing if the sniper's going to hit things or not. You're screwed both ways : either yolo it and commit your medic = risk losing your med "randomly", either don't commit your medic and put all your frag classes at a disadvantage for the push
-if you use a sniper to get the entry pick and then push 6v5 you have no way of knowing if your sniper will hit stuff during the push, and if he does not it's like pushing 5v5
-If something fails during a push you put yourself at a bigger risk than when you suicide a solo player because you are not set up properly to handle counter aggression
I'm not saying this can't be pulled off, but that the amount of knowledge required is much much higher. For each point, do you exploit a pick the same way regardless of what you killed? Do you engage the fight 6v5 or try to make it 6v4? Can you get your medic out if things go south? What if they have a sniper?etc...
It's not trivial to me (but i'm not prem lol)