Pretty sure most of the memes I have ever downvoted I didn't agree with. I have no idea how many downvotes it takes to get sent back to submission. It's happened to me twice and I know I deserved it both times.
If there weren't any alts and everybody had just one vote this wouldn't be an issue. Well, if everybody for sure only has one vote and you get dropped back to submission then you might have to rethink the meme idea or context.
However, knowing you can upset one person and they can kill your meme by logging into a bunch of different accounts and downvoting it. That is something that should bother all of us. No single persons opinion should be worth more votes on here than another's. Plus nobody should have to keep an opinion to themselves because they don't want somebody with multiple accounts attacking them for it.
The majority of people in this community are decent and would only downvote for a good reason. It's unfortunate some feel they can make up for a lack of social skills with alt versions of themselves online.