@
TheHypnotoad
Actually, Smogon usage tiers are determined by the
1695 Ranking usage rating. So you have to be a player well above average to even affect the tiers on Smogon. (Or by Smogon standards, the "average competitive player")
Smogon tiers aren't a simple popularity contest, it is a popularity contest weighted towards the best players.
The methodology and reasons are different. In particular, Smogon tiers are made because players wish to balance the metagame and change the rules in some fashion (notice the Prankster / Swag ban in the standard OU environment). Nonetheless, Smogon tiers effectively play the same role as tiers in fighting games: its the short-list of threats that you can expect in competitive play.
Just as I can guarantee Mega-Metagross on the ORAS OU Metagame on Smogon (a high-threat OU pokemon), I can also guarantee you that you will see Diddy and Shiek in the next tournament, because they are the current top tier threats in Smash4. If you want to ignore this fact, you're welcome to do so. But tier lists allow you to train and focus your skills against specific threats.
In any case, all games with more than 10 characters / classes will have tiers. Its a methodology that humans create to help us understand the competitive game and how to analyze other players. The purposes and interpretations of tier lists may differ from community to community, but tiers remain a universal trope across all video games for a reason.