It depends on game/implementation but client wouldn't really roll dices on their sides. Someone shooting a bullet that does 5-10 damage would tell server to shoot bullet and server would reply "you did 7 damage"

Especially on an mmo, there is no point telling a player that his next fireball spell will also trigger a "random chance to put a burn status on target". The client would start casting a fireball, which takes a second to cast and in that 1 second duration the server would decide what is the damage and if the spell is going to apply burn and by end of 1 second, you would get that information so you can see the damage values and burn icon on enemy

It is better to keep clients dumb if possible

Presumably nothing! But I imagine it was might have been impractical, given lockstep method is kind of predicated on "Do it because you can't afford to only compute and transmit from a central node."

In the era it was used, server chips weren't really a thing. So it was really just "the current decent CPU."