It's not, it makes no sense. They can post 100 posts per day without any of them being constructive or without quality whatsoever, and with all those posts they won't be able to rank up.
Give the new system some time, it will all clear up. Tho spamming is obsolete now, the only thing I see going on will be the account selling prices going up.
That's right, sooner or later those shit posters will eventually give up on making their way up to the rankings and will be forced to join social media campaigns as they will realized that they will not be happy on what they will earn on signature campaigns with their current ranks. The time since the new system has been implemented is not yet enough to eradicate all those members but we can see that it made a change significantly.