I could buff the player's baseline alchemy stats and nerf the tank upgrades? Do you think that would alleviate the issue?
I feel like something as crucial as the tank capacity upgrade is always going to be too useful to ever skip. It's the only thing that helps when fighting many enemies of the same type.
The only way I could see myself not saving for it first is if weapons had more upgrades that helped with stock consumption, but then I'd save for those instead, kicking the can down the road.
It feels like a similar situation to that build before you added cauldrons where tier 2 elements were an upgrade so I always got that one first, that's why I think getting tank upgrades from bosses or in the store would be better.
But if you want to keep them as an upgrade then yeah making the baseline better could make the alchemy upgrades feel like training wheels for new players? Like a safety net that's good to have but good players can play without, maybe.