Let's consider an abstract situation:
We develop a commercial plugin for Joomla that does something. For example it turns all normal links into SEO links (I know it's trivial but it's just an example). Now we want to reach people. We add our software webpage to the most obvious places like Google Ads, software directory websites, etc.. However the first thing that comes to mind is to actually let Joomla users and SEO folks know about this software. And then comes the problem: all such places (Joomla forum, various big SEO forums) prohibit advertisement.
What is the way to deal with that? It's quite natural that I want to let Joomla users know about software that might help them but at the same I can't break rules. I can think of tricks like creating topics that would pretend to not have ads (e.g. "did anyone use this plugin, is it good?") but I don't want to go that path very much.