What a shit excuse. So, are you saying that you won't add an extra security measure that benefits your users because "you are not like the other mixers/you don't want to be like the other mixers"?
Being different than other mixers is valid excuse not to offer Letter of Guarantee. For example ChipMixer does not offer LoG because it is incompatible with chip withdrawal idea. It would be nice to have an additional security measure but sometimes you just cannot do that.
I agree that the principle of this mixer is fundamentally different from the work of similar companies. But at the same time, it turns out that everything will be based solely on trust between the clients and the project team, but confidenciality and anonimius are very important..