Sharepoint.stackexchange (formerly Sharepointoverflow.com) is out of public beta, and we should be able to move or migrate questions from Stack Overflow or Server Fault, etc. to here, but I don't see that option....?
You are right in missing this point for "belongs on SP", but if you take a look at the bottom of each SE-site you will see that there are many more SE-sites than the five which are clickable. So only for these 5 exists a direct move.
I guess this decision once came from what have been the earliest sites leaving beta status and/ or which one are most useful to offer. Because it is not easy to fit in all non-beta-SE-sites in that form. So I assume you will get a status-declined on that request on SO meta.
I found this question on meta where the answer states that you should flag it as needing attention and there write where and why it belongs to. I asked it on meta to follow up the discussion (if there start any).