No you cannot post on Facebook and send bitcoin for support when Facebook can and does ban and censor, unlike here where anyone with an account can post whatever they want and it will always be here, and the same for comments, that's why Steem wins hands down. Furthermore, downvoting is simply another expression, and those rewards are to be voted on as such, just as every upvote for another removes rewards from all other items in that pay period. If you want a dysfunctional platform that let's people express themselves only by upvoting go to whaleshares.