You realise USF has a significant advantages over Ostheer right? While he's building T1, you're building a squad. While he's building his squads, you're building more squads, you'll have 1 up on him (when you tech up, it'll be 2 up). Those 3 squads of his (+T1) are 800 manpower, while yours are worth 720 and as far as core infantry go, are superior to his. You also make it sound like you just move in a blob, in which case Ostheer has no choice but to get an MG 42 and hope he gets the jump on you first.
1- Grenadiers and MG build time is faster than Rifles, and cost 40mp less. I let you watch some replays or live games to see that every faction has more or less the same number of unit in the field in the first couples of minutes of a game. (if not spamming pioneer or RE)
At the 2nd grenadier built, you've spent equal amount of MP with USF. You've just paid 10 fuel more.
Pioneers are completely underestimated by many Ostheer players, their flammer upgrade is probably the best first ammo investment of all factions.
2- You're not supposed to cap at least 3/4 of the map in the first 5 minutes in order to have a chance to win the game as Ostheer. you can sit at your cutoff + fuel/munition while the USF need to control the rest of the map to keep his chance to win. That's why you start with the possibility to build a MG and USF not.
So in term of time, you have plenty of time to consolidate your sector before the USF comes with that number of units. That's why I catch so many Ostheer overextending, they believe they can early push and get cut from their line of support.
4- If I was blobbing, I would lost 100% of the time. Who can believe you that a blob of 2 REs + 2 or 3 Rifles can enter in a MG cone of fire and kill it when it is supported by 2 grenadier squads. Maybe it works with BARs or maybe it works with 1919, I don't know I'm usually not blobbing - And if I do, not into an MG cone of Fire.