I have created this question because of pt2 - OP not having 15 reputation cannot upvote (real situation you can find in edit history), but I have thought this topic through before asking, comming up with four points, the first being just obvious, second being the reason and last two being my struggle understanding what is happening (why is SE set up as it is). Finally boiling it up to suggestion, which was not so clear at first, so I had to edit the question after Vogel's answer, to make it clear, understanding it was not so - suggestion (feature request - marked as such from the beginning), not just asking about the state. This is, btw, the reason I did not accept his answer - not answering the full content/question - but the very fact also brings thoughts and questions about the very topic and possible answer to pt4, because I was tempted to accept the answer as generally accepted without trully accepted by me. That is interesting possibility, but I stay firm: that is not the correct use of accept - I would just get rid of it, not mark the correct answer (there is still none).
I would gladly accept Andrew's comment answer: It has been requested since 2009, and declined in 2012, because to me it reads: it may not be viable for every SE sub-domain and even if it was good for CR, it won't get implemented, because... ehm, read the comments below the question for yourself.
Disecting the points
- pt1 - self-answer - obvious
- pt2 - not enought reputation - I stay firm, they should be allowed to do so. Prohibiting users to upvote answers of their question only discouradges them to ever upvote - because they cannot do so now/immediately and won't notice and understand when they can, because they are currently denied the experience from the very beginning. The only reason for this (counter)measure I can think of is that some users could create alter-egos to upvote their own questions or answers to gain reputation. But finding those and deleting them will remove all upvotes making this strategy not usefull... unless the moderators or AI cannot cope with the sheer numbers (which could be the truth for SO, althought certainly not for CR and many other SE-subs).
- pt3 - that is the plague, partially created by what I have described above in pt2 and Vogel612 prtially addresses in his answer too.
- pt4 - and that is what I think many do and I myself was thinking about when considering to accept Vogel612's answer. NO, that is wrong. I can imagine that my own drive for the suggestion could be to get upvotes on my own answers and I cannot fully deny that, I am still a human, but my true drive was to make it even for everybody, to give everybody what they deserve. The question could still be about the numbers: 10+15; and about what to do when OP later accepts different answer (my solution: keep +10 upvote, remove 15 for accepted ... or maybe remove even less, because it could have been the correct answer at that time, but not today, because e.g. we got new C++ standard).