No they aren't. A self selecting poll isn't one you choose to fill out if you are randomly selected, it's one you choose to fill out and has no control by the person putting the poll out as to who can and can't fill the form out.
It's a technical term that means something when it comes to the science of polling. Sort of like how Theory means something different when you are talking about common usage versus scientific usage.
Sure, and it's fine for that.. I just thought it was interesting to consider what it can and can't show... and the flaws of the type of poll that it is.