You do need good "solo laners" though, its core to high-end play.
It's not the same term as last-hit MOBAs where your "laning champion" exists just to control one third of the map - in HotS, a solo laner exists because they can cover TWO lanes simultaneously in the early game while the other four people constantly roam and apply pressure. Heroes like Arthas, Blaze, Yrel, MG, Malth etc are classified as such because they (a) have good waveclear that allows them to quickly mop up minion waves and rotate to another nearby lane to get that wave's exp as well, (b) they can bully their solo opponent effectively, hoping to force them back (and thus miss exp), and (c) have enough self-sustain that they can keep in lane farming efficiently as long as possible, while also being difficult to gank.
You may not like it, but that's how the game works