Have used TA singles on a lot of bikes. Never a problem. Not necessary to have the FD as a chainguide.

People take bikes to extremes. I know of one case where there was a real, not imaginary issue with the setup we’re talking about. Rider was using a fixed wheel and liked to ride mountains. 42x16 up mountains is a bit severe but tastes differ. Using a chainring with extra unused holes for mounting another chainring the 42 broke. The unused holes acted like perforations. Failure occurred after just a lot of mountains and when the ring was about to be retired anyway. Finding rings meant to be used as singles solved that problem completely, many more miles and mountains and no more failures.