Yeah and as far as I understand the difference in power actually becomes larger in relation to the same amount of point differences as you cross Stages and Realms.
So for Houtians more than a 10 point difference is different stages - EH 10-20, MH 20-30, LH 30-40, PH 40-50. So yeah it makes sense that a 10 point difference would blow Muchen's arm off - to him it's like Being a LH and meeting fists with a PH.
But if we look at Mortal scaling which goes from 1-10, realistically a 1 STR Mortal would be the weakest an active Mortal MA can be (still not weak by Mortal standards) while a 10 STR Mortal like we see in the Prologue can lift a 700lbs stone above their head. That's of course not counting the alchemical reinforcement Great Clan heirs go through and whatnot but it's the only estimate we have. I will assume that a 'weak' 1 STR Mortal MA can still manage to do 100lbs because otherwise they are NOT built for this life.
But as we all know, no matter how strong you are as a Mortal, you will never be able to explode someone's arm by hitting it even though you could be STR 10 and they STR 1. So crossing a Stage or Realm apparently matters a lot while the numbers might look the same.