Posting a public message saying "I sent you a private message" is ok once in a while. The majority of the time, though, it's repetitive and entirely unnecessary. Most people understand this and use it sparingly. It would become a real problem if everyone started to do it with every pm they sent as you seem to think should be done by posting 10 in a row. The flashing yellow icon will tell the person they have a private message waiting. Some will even receive an e-mail notification. An additional post in the public forum is redundant, and especially on a thread where someone else has already posted the same note. It's a post meant for only one person yet will be read by 1000+ people, wasting their time, and remaining in the database forever taking up space, slowing down searches, etc.
I'm sure you didn't consider it a problem. Nobody is accusing you of doing anything wrong and there's no need to be offended because a post was removed.
Your other post was not deleted, only moved to private message. Those notifications are still working so you should have received an e-mail. It was moved because it was in the form of an advertisement, linked to your web site, etc. I don't have a problem with vendors using the site to get sales leads and using unlimited free private message services, but nobody tunes in to watch commercials so the public posts are strictly limited.