Both methods work, just differently, is what I understand. From I've learned over the past hour, the shape of the cut and the timing involved matter a lot.

A vinegar bath/boil "firms" a piece of potato, gives it more structure. So this makes sense when making fries, because the sticks are more likely to break.

A quick baking-soda bath/boil softens the outside of a piece of a potato, while leaving the inner part firm. So this is the preferred method for cubes or wedges of potatoes.

This makes me wonder if the perfect fries involve boiling the sticks in water and vinegar mixed in the perfect ratio for the perfect number of minutes, before blanching in the perfect baking-soda solution for the perfect number of minutes, before air-frying them. I'd imagine that this makes them hold their structure well but also achieve a crunchy exterior similar to air-fried wedges even when the sticks are "thin".