it is not completly true - if you want to send a sliced file which used the type ‘PLA’ for example and in the AMS slot is ABS selected, Bambu Studio (or also the printer itself) will not let you select that slot for the sliced file. At least the type has to correspond.
If you save a custom filament preset with the type ‘PLA’ and on the AMS select ‘PLA’ as well but in reality using a different filament is another story. Nevertheless, I would be careful to completely ignore the types as there are maybe internal logics that may trigger some behaivors of the printer (if not yet, maybe in future updates).