It provides a goal to users to reach. The apps not that glitchy for me, only very unoptimised, but those problems are not existent for people new to art as they don't have the skill to make their art more detailed which causes the lag.
Without the ranking system new users would still be in the shadows. But with more people they won't be for long if they just keep on posting and keep chatting to other users. I have yet to see any jealousy due to ranking either? ranking was and still is a good idea. Advertising this app as of right now would do nothing but help it.