I don't think anyone is making that claim. I certainly aren't. But it's undeniably a big factor when he comes up against certain defences.
(One Liverpool centre back simply couldn't cope with his strength and yielded him the entire field).
As for Lukaku, best in England, 25 in 36 for Everton, last season at Inter 24 in 36, so very comparable.
His international record is just stupid, and at 28, 64 goals in 98 games.
At Chelsea he will be a big danger, little doubt of that.
As for the Liverpool centreback, I remember Hansen saying the forward him and Lawrenson were most wary of was Cyrille Regis, but that fortunately Cyrille was unaware just how much trouble he could cause, so the tactic was to be nice and simply contain without fouling him for the first 20-30 minutes, and after that things tended to get easier.
And that approach could likely be successfully applied to a lot of situations in life, not just football.