Why would anyone use this over Proton Mail or the gazillion alternatives if it treats people like shit.
Arguing about what people mean is futile. The point the other poster is making, and you've now agreed to be true, is that FOSS is software and a service is a service.
Most services powered by FOSS offer a free service as a taster for the paid service. The money made in the paid service tiers pay for the free tiers. Hopefully.