Overlapping fields of fire, mines, rifle nades, mortars, snipers, etc can fight rifle blobs if you have perfect positioning.
Smoke negates snipers, mortars are woefully unreliable against moving units like rifles, rifle nades are plausible, but if you have 5 rifle squads throwing smoke simultaneously, then its impossible to deal with. + Rifle
Mines are plausible but Wehr is just about as much active crowd control as it is passive.
I'm not saying that its impossible to deal with it, it is just really difficult, especially when it doesn't take ages to build 5 rifle squads in earlygame but in order to build the counters/get muni, it takes a whole lot of the game. And, as you said, it also requires perfect positioning. Keep in mind that even then, you don't guarantee squad wipes.
I have beaten back rifle smoke pushes in the past, but it required a lot of MG micro from me, and an opponent, who, admittingly, was a bit inept at attacking.
See when the mainline unit gets an "I win" button against crowd control - it can only lead to one thing - blobbing. I'm perfectly fine with Ami Shock units such as LTs and Captains getting smoke, but rifles getting smoke is simply crazy.
Keep in mind that, if my MG gets flanked and killed, I'd actually think "Well Played opponent" even in the state rifles are in atm. But if it comes to blob->smoke, I feel cheesed, my POV tho.
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(And even then, my point that you don't need smoke to deal with MGs still stands - why you need your mainline to have easily deployable shot blockers I have no idea, I reckon its bad design and is simply not necessary - my rank atm proves this, I don't play as much as I would like so I feel Im underrated atm - its kind of a similar problem to putting flamers on all of your mainline units.)