I don’t disagree with much of anything you said (and it doesn’t sound like you disagree with anything I said either) aside from the classification that it’s all spam. If I make one on-topic post to a community and you don’t like it, that doesn’t mean it’s spam. If I made 2 posts to to different communities, you admit it’s not spam. The problem isn’t the users who are posting, and blocking them isn’t a solution, at least certainly not a long term one. The problem needs to be addressed at a fediverse level, and not at a content creator level.
If I send out an email to 100 of my friends inviting them to a party and they all wanted to get that email, that’s not spam. If I send out 100 emails to the same people asking them to buy essential oils, that’s spam. It’s not the amount of content that I send, it’s if the content is relevant and appropriate for the audience that defines if something is spam or not. I agree that it’s very annoying to see the same content in dozens of different places here, but to call it spam is to place the blame on the poster, and that’s not where we should be focusing the blame. Dance around it all you want, but posting on-topic content to the correct places isn’t the definition of spam. Period. The only people calling it spam are people, like yourself, who don’t know what spam actually is.