The switch that makes sense
If MaxRewards' account linking gives you pause, StackEasy is the credential-less alternative: it recommends the best card to use from a wallet you build yourself, with no aggregation and no bank login.
The honest catch: MaxRewards' signature strength is automatic offer activation across Amex, Chase, and Citi, and StackEasy does not replicate that, by design. If that automation is what you value most, MaxRewards earns its linking requirement.