As a matter of self upvoting I think it is a little illogical. It can be really done with have multiple accounts but my point is somewhere else.
I think that making self upvoting so obvious this has become a common practice here. Because almost everybody upvoting themselves, the part of distribution of rewards is not circulating between people it is in eternal cycle on one account.
Technically self upvoting can be replaced with delegating some SBD from reward pool proportional to your SP per day. In extreme case if all SBD from reward pool is distributed in this way no SBD will remind for upvoting each other. Steemit is then degraded to a facebook level where nobody get anything for social interactions. Even worse, those who have a lot of SP will have it more and more in proportion with those who have few SP.

This promote a stand that if you just have an account here you automatically get reward for doing nothing on the platform. This contribute to growing a wealth gap between people here on Steemit.

If direct self upvoting is not possible on the platform than smaller part of population on Steemit will use this a little more complicated way of having multiple accounts to upvote themselves. So sitting on the platform upvoting shitty posts of no value and sucking reward pool (what's is most people dislike here) will not be so obvious option. In majority people, especially newbies, will have to move their asses and do some work to provide more valuable content to get upvotes and this is a social dimension, where Steemit can benefit.
Gradually smarter ones will discover a way to upvote themselves (multiple account stuff) but those who established a flock of active followers will continue earning rewards through the social interaction of rewarding followers and friends for providing good content on Steemit.

This will provide more good quality posts, less shitty stuff and better social health on Steemit.

@knircky if you think my ideas are sound, I will be delighted that we can start a campaign about this matter, because strength is in numbers and as more and more people interact and cooperate results can be amazing.

Which other problems, you mean, self upvoting create?

Be good! :-)