Chemist as a healer could work if it was like Ninja.

Either hitting different mixes before throwing/casts or having it interact with the buffs it gives. Like it gives out “Regen Salve” and hitting the target with another skill could expend it for burst heal, shield, AoE heal.

The problem comes from people having to remember the right order and mixes. And NIN mudras get enough complaints so having to cheat sheet a healer? That wouldn’t get cleared.