i thought it was just to ease your body into it because maybe the transition is uncomfortable (like what MarBaSxx is going thru). Once I OD'd on the stuff and it was kinda crazy, I meant to take some other research chem i forget which one but accidentally did a 2nd dose of T3 at night and i felt way stimmed up, sweaty, heart racing, couldn't sleep for a little bit.
Anyway i'm not 100% sure on the reason for the tapering nobody ever seems to talk about why, just to taper. So i just do it. I really don't care about T3 enough to start experimenting on myself.