Providing a coupon code to receive a free premium membership is a trait of advertisement imo. I think that's the reason why.
By just seeing your post with bold Free Coupon title, I can already say that your intention wasn't really to inform about the coin being listed on your service, but to advertise your service directly with a promo.
Yeah, this is probably the real motivation but why permaban for 12 replies? I think this is a very hard sentence, IMHO probably a soft ban with a real motivation is more educating.
Also posting the same message in multiple places: spam...
not good behavior in the slightest.
The message is not the same, the external link is changed every time with the coin in objects on the thread.
For example:
Dash Announcement Thread => example.com/dash
Litecoin Annoucement Thread => example.com/litecoin
And according to what is said in the official spam thread in that section, this action is allowed.