How did I get banned for life from posting in a few subreddits?

Yesterday I invested (time!) in a couple of new marketing strategies for the TechTok product. One of them was writing on subreddits.

I’m not a Reddit power user, I'm normally a read-only one and rarely engage with any post apart from upvoting or downvoting.

My initial approach was to find the communities (subreddits) that would be relevant to post about my tech newsletter (TechTok). So I've found:

• r/startups: found a great thread to engage and do a little elevator pitch
• r/technology: it’s probably the subreddit I check the most, unravels a ‘before it was cool’ side of tech
• r/technews: it seemed perfect for my tech news product subtle mention
• r/SideProject: while looking for other hustlers support
• r/learnprogramming: wild guess but the audience would be the right one for TechTok

My approach was: “let’s give it a personal spin on these posts” with the idea of what is it that I’m trying to solve for me that could work for others. So the titles of the posts followed something like: “I used to wake up and check Instagram every day as a first thing in the morning. So I've built a product to replace this habit with something more useful: tech news!”

The results were: banned for life or “permanently banned from posting” from r/learnprogramming, r/technews and r/technology for violating the rule “No Spam or Self-Promotional Posts”.

In a way “fair” but on the other hand “harsh”. What do you think?
It says “Don't post links you have a financial stake in or otherwise benefit from.” - I get that if people sign up for my free newsletter and eventually I monetise it I would get something out of it.

On the series of “I wish I knew this before” I found this Quora answer that provides 6 steps when writing a post on Reddit that are valuable to know: https://qr.ae/pspjlF - Between (1) “Choose the right subreddit” and (5) “Timing is important” I think I did well. What apparently went wrong on my what I thought to be a harmless post was (6) “Follow community rules”.

Will I continue to use Reddit? Yes. 100%, I can still read things if I keep a legal 200-meter distance.