Alchemists and potions without spell equivalents

Plus it isn't trivial to get 3 levels of a specific proficiency.

I disagree.

  1. "Civilian" characters get four free proficiency ranks at level 0 in lieu of Adventuring proficiency.
  2. Alchemy is a general proficiency. Any PC with Intelligence 16 or better starts with 3 general proficiency ranks at level 1.
  3. The Alchemist specialist has Alchemy 3 by definition. There's at least one for hire per month in any Class III or larger market. Their wages are 250gp/month, sure, but with the average Fighter collecting 1600gp by the time he makes level 2 (assuming 80% of XP from treasure), 250/month isn't really cost-prohibitive.
Between those three things, I would expect every adventuring party to have at least one rank 3 alchemist available if they want one.