Nasus is irrelevant at all stages of the game
I would like to start by saying that "infinite stacking" is a lie. Nasus does not have infinite mana, so he can't stack his 'q' forever. And, like most champions, Nasus uses more than one ability in lane, which also drains his mana. Furthermore, if you're stupid enough to let him afk farm and not secure kills and/or an objective, you deserve whatever happens. Finally, true damage, %health damage, grievous wounds, last whisper, crit, etc all make Nasus super easy to kill, regardless of how much armor he gets. And these things are not hard to come by at all. So please tell me why the hell would is everyone so concerned about Nasus? If anything he needs buffs so he's actually able to contribute to his team.