In my country, there are too many contacts that send advertising messages to a large number of personal contacts who are constantly being annoyed by receiving such ads. It even get worse when you live in a large city.
Textra can (I hope) add a special feature to report such contacts; based on the number of reports of an annoying contact, Textra can automatically consider it as a smap-sender and prevent its notification for Textra users; instead it can put its messages in a separate silent folder/inbox.