Lol, he lost 5 squads in total, I can bet my ass safely that I didn't lose just by sturmpio build. MG 34 and volks would have lost me the game as well, I had north side Kharkov.
All excuses and possibilities aside, I didn't play at my best most certainly, but telling me my build was 100% lost case when I wipe 3 of his units isn't that big of statement my friend.
You may have not lost entirely because of a spam sturm pio build but it definitely went a long way to causing it. Volks help with capping since they are a lot cheaper than sturmpios and can easy force off RE's. They are cheaper to reinforce so less of a mp drain. They are also reasonable at long range when in cover, even vs rifles. MG34 despite its weakness when compared to the mg42, is still decent at suppressing infantry. Using suppression combined with Sturmpios is a deadly combo and can inflict lots of kills / damage if the opponent doesn't retreat when he becomes supressed or pinned. Sure he can use smoke but there are ways to counter that (mines near mg34, volks with incindi nades into the smoke, soft retreating mg34).
However, I'm sorry to say that the main reason why you lost this game (and probably many others) is that apparently you don't like to admit that you fucked up, whether it is due to build order, micro or whatever. Until you stop thinking the only reason you are losing is because "OMG USF SO OP" and stop being basically a twat in game, then you will never get better. Attitudes like "because I did almost everything right, he did everything wrong," are a perfect example of this. You did so many things wrong and have no right saying that he was the one doing everything wrong.
You should be analyzing all of your games, regardless of it is a win or loss so you can see why things went wrong and why things worked. You can figure out what can be done better, when the best timings for various units are. Posting your replays up for advice is really useful as there are many people here willing to offer help. Watching streamers play the game can help a massive amount as you can pick up build orders and tactics for various maps, as well as how to counter different build orders / units. Most streamers will often help if you ask questions about the game.
If you are for example having problems vs USF as OKW, play USF until you get beaten by an OKW player and then see what they did. If you are not having much luck in getting matched vs okw players or whatever, then ask people on the forums who are better than you to play vs you so you can improve.
If you get matched vs players significantly better than you, its always a good idea to ask how you can improve or what they think you did wrong.
Last point, for the love of god please stop making all the fucking "ALLIES OP" threads. Imo game balance has little to do with you losing right now.
Edit: In before calling me an allied fanboy.