Right now, with how credos scale notably in difficulty as you acquire more now that credo suicide is obsolete, your character line makes permanent choices on what you're able to realistically reach. The most notable and reasonable switch up for a character is switching from aiming for blacksmith to aiming for cave hermit. Picking up mystic after you've gotten multiple "un-necessary" credos is absolute murder considering mystic is notorious for being one of the hardest out there. This lack of flexibility also impacts existing character's ability to reach newly introduced credos since their choices are currently permanent.
If a credo doesn't support any others you own you should be able to revoke it. Due to the gravity of this choice, it should start a 24hr counter or some such that can be cancelled at any time to prevent the majority of misclicks.