This is open community, general discussion board. There is rules for each section.

SELF PROMOTION: 

• If you're advertising a game, then don't post here. Use the Release Announcements board to self promote your itch.io projects. Follow the rules there when posting.
• Advertising links to your discords/twitch/etc. not allowed
• Game jams can be shared in the jams forum

This is from general discussion. And I believe it is safe to say, that "game" stands for all projects.

Open community is not frequented that much. Just look at the view counter of threads. Most people seem to come for one specific thing and go away after that.

Some self promotion is kinda tolerated. Technically it is not allowed and if you overdo it, the nice mod might warn you a few times. You can lose posting privileges for spamming and continous rule violations. So basically the stuff you do see, no one bothered to remove it.

And I doubt the "effectiveness". If someone makes noise, one might have a quick look and promply ignore that noise hence forth. As I said, look at the view counter of random threads. Coincidentally meeting someone interested in your stuff, by aimlessly self promoting is not very likely.

In other words: better promote your game at places where people want to read about your things. The designated section for this on Itch is the Release announcements.

Or be active at discussion about things you also make. But no one want's to constantly hear about your game pitch, so you better be really active in that discussion and not use it as an excuse to pitch your games ;-)