It's fine, and people do post their project announcements here. But most of them are after months or years of other posts on the board discussing their game development issues and successes. To come in and post a bunch of shouting “look at my game!” with posters and links to your channels, well, let's just say it's not really focused on game development.
As a game development community, we'll happily talk about issues you face in your algorithms, bugs in your graphics systems, gameplay logic troubles, business and marketing strategies, and brainstorming for gameplay ideas. We're not really the place for announcing that you made a game, it happens, but that's not the focus.
It is wonderful that you want to join in the community, and you're completely welcome to discuss all your game development concerns, or support for other developers with questions or issues. That part is great, and I for one am looking forward to more of that kind of posts from you.