No, spin & speed works togheter, flat hitting yes H3 has less speed, simply look chinese NT players when are smashing change the rubber side to hit with the red one.
It’s just my personal opinion. To me, with H3, it’s a lot easier to, say, (1) give the ball as much spin as I want without constraining my body swing & without putting too much forward power into it, (2) hit the ball very hard and still gives it a lot of spin, either in a counter or in an opening, (3) kill the forward power in the ball by a soft block. Hitting hard without spin is a little harder but it’s still there. Apparently everything is relative, not 1 and 0. And I didn’t imply it’s best at everything. But you don’t need to play brute-force with H3 as people say. It’s actually a lot easier to create variations with H3.
And it’s probably just my personal style anw