As a scrublet-tier playing full alternating I'd say alternating, to some extent, helps with endurance.
It also helps with consecutive triplets, since you're used to the ZXZ XZX whereas single-tappers might(?) have trouble deciding whether to ZXZ ZXZ or ZXZ XZX. On the other hand, it really screws over the double stacks (at least for me)....
From what I see there's no huge downside to alternating, accuracy might be one but bleh that just takes practice. There are maps where you're forced to alternate, so if you're comfortable alternating there's no point in going back to single tapping. If it's causing problems for you, then you probably should (though idk what kinda problems, someone could point a few out...)