Jd Smith1
Hero
I don't think it's a good house rule because it devalues a number of things that aren't overpowered to begin with:
I don't ascribe to the idea of hp as primarily meat, but even if you do, it doesn't make sense that a frail wizard with 8 Constitution will have the same number of hp as an indomitable barbarian with 24 Con at 20th level. That's like saying Ali could take the same kind of impact as Tyson at the height of their respective careers. They're both legendary boxers, but no way Ali could take a hit like Tyson. They literally weren't in the same weight class.
- Bigger hit dice
- Toughness feat
- Hill dwarves
If the goal is to prevent hp bloat, then just cap hp at a certain level. Given that it sounds like you give characters max hp every level, if you cap it at 10 they'll be in the ballpark of same hp as if you went by the book, albeit 10 levels sooner than going by the book. Or just don't give them max hp every level.
Punching with a padded glove is a far different situation than being hit by an axe, arrow, or bullet.
IMO the difference between the wizard and the barbarian would be 10-15%, tops. A barbarian would be harder to hit, though.