Earlier quoted context omitted.
Not an excuse. It is not okay to abuse someone just because they can ask you to stop.
Describing those 'ads' as "abusive" is quite a stretch. It's like going to the store page itself and complaining they're telling you about products they sell. Particularly when you can easily disable them. No other game client I know of offers that.
On the other hand, I don't classify what Steam is doing as advertising. When I open the Steam store, it's because I want to see the games it has on sale. It's not advertising, it's the exact information I asked for. It would have been advertising had it kept spamming me with game deals while I'm watching a film or something.