Actually, this site is usually the best, and Facebook (the latter might reflect my audience).
Reddit subs tend to censor any attempt at self-promotion, which you can't blame them for, I guess. And StackExchange is the absolute worst. The level of asshole-ness there has to be seen to be believed.
YC/Reddit/SE being good/bad/worse for self-promotion seems to be 100% in line with the intended use of these sites.
Most of my readers come from HN, reddit or substack itself. Now it's mostly Python so it makes sense a tech oriented medias will be reading more about it.
Still, the ban on substack by twitter means that, while a #python tweet gets some view, the same with an article to substack tanks bit time.
So when I post it, it's congruent.
Basically, either you find a way to cheat, or you climb the ladder. I'm terrible at cheating.
It's always been very difficult to get people to leave Twitter. This is why their ad business is worth so little. Advertisers pay for clicks, and Twitter just doesn't deliver them very well.
However, if I link to an external article or something, the percentage of people who actually click on it is relatively tiny.
Twitter has been completely worthless anyway for promoting my Substack channel. In their Dashboard, it doesn't even show up in the top five referers.