This can be upsetting to some people who want to roleplay classic fighters for example, not potion-drugged gigachads with 18 in every ability score. It is even more concerning how they'd balance the game around such shenanigans. Something tells me they won't at all.
That is a good point.
And that's totally cool if that is the character you want to roleplay as - an austere warrior who eschews all drugs because [Background Reason] - so no Elixirs, no health Potions, no invisibility potions, no resistance potions - I assume weapon oils are fine.
However, it doesn't stop you from using Magic Items armor, or weapons that increase certain stats. Unless that is also part of your restrictions. In which case I would say you may have chosen the wrong class and you should look at Monk instead or Barbarian.
