If you have 2 complete roams before the tower falls, that is ok.
if you have half a roam, that is not ok.
The problem with the "split pusher top" meta is this:
starting in the early mid game, If the other guy kills you, he takes a tower.
if he can beat you and doesn't kill you, he takes tower slower.
if you go elsewhere on the map, the time you have to push an alternative win condition is super low because he takes tower really fast, so you can't do that either.
you end up with having to choose a champion that can beat the other guy 1v1 and take towers fast. And both of you are playing the same game and non of you have the option of doing anything else.
In addition since tower taking by those characters is so fast and their ability to both snowball themselves foreward AND either trade 1 for 1 when they get ganked by 2-3 people or just escape is so obscene, they end up making the game about themselves, where it doesn't matter what mid and bot are doing, because the enemy top has won and now you have to spend everybody to deal with him while the rest of the map gets swiped for free.
I.E. the losing side's team (remember losing in this case can be at level 5-6, 5 min into the game) is on a timer, and the moment they cave in to the pressure they start losing.
This is basically a result of there not being good "not good split pushers" that kick the shit out of jax/trynd and the other "duelists" in the mid to late game.
EDIT: ofc this is all deep in the "used to be" since we are now living in the "bot lane objective and rotations snowball". Which is btw far more healthy for the game as a whole.