Can someone accept other user old question? Example:

If "A" have a question posted. Then "B" answered the question (and it is good and acceptable). But "A" didn't open his/her account for 1,5 years. Can someone (say it "C", high reputation user) accept this question cause it is acceptable answers?

I ask this because there is a lot of user aren't open his/her account and didn't accept the answer, even it is acceptable.