We've had outright spam here once. We deleted the post and deleted the account.
I felt like this post was topical enough... a 1-person operation just released a brand new piano app and thought to announce it on the digital forum. I was OK assuming good intent here, but if general sentiment turns the other way, we can revisit.
As @iternabe says we can also potentially tag such posts both so that they will be excluded from All Discussions and so that users can ignore the topic completely. In general, need to invest a bit into all the Ignore feedback I've received — once I wrap up some of the loose ends with the recital!