First, I'll answer the general question: Is it OK for people to comment on one's accept rate?
Yes, it is.
It is inappropriate for people to bring it up in an answer, but the "add comment" feature is for commenting. It is the only non-answer way to actually communicate with someone. And a person who doesn't accept answers needs to be communicated with. If not comments, how would you suggest informing someone about the accept feature if they don't know about it?
Now, I admit that people talking about accept rates does sound like someone trolling for rep. After all, accepted answers are not only worth +15 rep, that's +15 that doesn't get capped at 200. But in general, it is perfectly fine to mention someone's accept rate in a comment.
There are extenuating circumstances that can make it inappropriate. It is entirely possible that a person simply hasn't received many satisfactory answers. Perhaps they asked several questions that went unanswered, or the answers were unsatisfactory.
Now, on to the more specific question: Where do you personally stand on this? I know you didn't ask, but you did use yourself as a specific example. So you left the door open for this.
You've asked 8 questions. You have accepted 1 answer. Namely, your own. FYI: accepting an answer to your own question doesn't give you rep. That's not to say it's wrong; it's perfectly fine if you feel that your answer is the most correct.
Actually, let's look at this question that you answered yourself. It may be telling of a problem.
Your answer was specific to Win32, using Win32 functions and such. Yet your question never once mentioned Win32. To be fair, you did tag the question Windows, but there is a difference between "developing on Windows" and "directly using the Win32 API". For example, since this is a game development site, "developing on Windows" could easily mean that you use DirectInput.
So your question was incomplete. That is why you did not get appropriate answers.
A second question that received multiple answers was the one about keyboard combinations. The comment under your question asked for something very simple: clarification on your API of choice for input. You did not reply, nor did you provide this information.
Despite this, you received several very good answers, detailing how to go about doing exactly what you asked for. There is no reason you could not have marked one of those as an accepted answer.
Then, there is this question about DirectX versions. Quite frankly, that is not a question; that is a rant disguised as a question. It's about you not liking that Microsoft is trying to phase out a 10 year old OS by not allowing newer technologies and APIs to run on it.
I can tell this not just by the language you use to ask the "question" (for example, the pointless use of bold-face text for "if you're running Windows 7!"), but also by how you respond to answers that don't agree. AttackingHobo pointed you to the Steam Survey about DX10 availability, and your first response was to talk about the much smaller DX11 availability. Why? DX11 is only a minor change to the DX10 (in terms of the overall API. Most DX10 code can run as DX11 with at worst a couple of changes), so if you want to code to DX10, there's no real issue.
You did not find any of the answers acceptable, even though most of them made strong points. Granted, as your question was less a question and more a rant, it's hard to say what qualifies as "acceptable". Even so, the blame rests on you for posting a rant rather than a question.
Similarly, I find the tone of this question on having a W component to be... defensive. It sounds like a question that you ask when you think you're discovered something cleverer than most of the code you've seen. Look at those silly guys, carrying around 4D vectors, when I can make do with 3.
Since nobody agreed with this notion, nobody got the accept check. Indeed, Maik made a great point that torpedoes your idea entirely for any use of SSE or similar vector intrinsics. You would lose lots of efficiency by trying to do matrix multiplies your way.
Now, this is not mindless bashing of you. I could very well be wrong about any of the previously stated ideas about your questions. But it seems to me that some of your questions are looking for validation for ideas you already have, rather than actual unknowns that you want answers to. And thus, when you don't get that validation, because others have different opinions about things, you simply don't accept the answers.
Other questions of your seem poorly specified. As such, nobody posts an acceptable answer because you haven't asked the question very well.
Therefore yes, I would say that it is entirely appropriate for you to be called out on your accept history.