"shouldn't" is not the right word to use here.
it is basically about when you want to receive bitcoin payments. for example if you want to cash out from a casino that casino may not support Bech32 address format so you are forced to give them another format (the legacy starting with 1 or 3).

the best solution is that if you are already using a wallet that supports this then use that anywhere that you can so that you can use the benefits of it such as a smaller transaction size hence a lower fee but also keep another wallet so that you can still receive bitcoin in case you encountered a problem like the payer didn't accept Bech32.