I have seen plenty of events posted on here with no problem and I know they aren't sponsors. For example, the SED drift events are posted on here every time there is one. People say come to the event. I don't know what you posted, but if you were pumping your shop, maybe that is why.

As a sponsor, I don't see an issue if you are inviting people to an event, but if there is promotions other than that in it, it's a little different.