I often talk to people who, when it comes to use tumblers, don't really want to bother using Tor. Especially because they don't need 'absolute' privacy
Honestly, using a mixer in a useful manner already requires a non-negligible amount of time and effort.
UTXO management, change management, managing vouchers and private keys, tracking how much time has passed since your deposit...
Adding 'Download and open Tor Browser' in the mix has virtually no effect time- and effort-wise, in my opinion.
You can even bookmark the ChipMixer link - I'd actually highly suggest that.