This is probably way more complicated than this, unnecessarily for the most part.
Single tapping does improve your streaming, proper singletapping that is.
Most people use wrists and arm to support their singletap speed,which is fine, though if you look at the doomsday for example it's all finger.
You can try it out, pick a stream map, put HT on, and try to singletap it with your main finger, while holding your other finger down on another key.
Alternators can also levitate their wrists making their alternating motion different from streaming but I guess it's preference.
I've had a conversation about this recently, i've tried pretty much both, but I singletap with wrists.
I will take it in consideration.