It does sound to me like a nefarious plot (but I'm making this comment in the interest of hearing an alternative explanation).
BTW I have carried a bag myself (lived on commission) from cold-calling up to closing large deals. So this isn't some "commerce is crap" / "I hate salespeople" knee-jerk bullshit. Shoveling turds into my inbox is gets you on, well, my shit list.
To me, sending me automatic mail I didn't ask for is being an outsider and adding to my todo list.* This is a hostile act, basically saying you do not value my time.
So when you tell me that you get a list of names and just add them to your spray-n-pray list, I can only consider that spammy activity. And when I think of it that way, maintaining a "don't harass these people again" list doesn't sound like a kindness, it sounds like you did it to avoid getting sued, i.e. for your benefit, not mine.
As I said, I'd be interested to learn if there is a more charitable way to look at it. Because the way it looks to me, it's all about you and you don't give a shit about the people who receive your messages.
* there is legit unsolicited mail, for example if my pal Alice tells Bob, "hey, you should ask gumby your question, here's his address". That's by definition personal and low volume.