Smeargle is terrible and outclassed because unlike the other suicide hazards setters, it labors to keep up hazards against a Defog Arceus, or a defensive Mega Salamence with more than 274 Speed for that matter. By contrast, Cloyster has Shell Smash and Skill Link Icicle Spear to pressure all common Defog users barring Water Arceus (which it still gets 1 hazard on), Greninja has 123 Speed and therefore access to a much faster Taunt, Deoxys-S also has a fast Taunt, and Scolipede has Speed Boost and Endeavor to punish any Defog attempts while still guaranteeing at least one hazard. Scoli also gets Pin Missile for Lati@s. Smeargle cannot do any of that. The best it can do is slow Arceus down with Nuzzle, then Taunt it, but two turns is a lot for something as frail as Smeargle. You're never getting more than one hazard with this vs. a competent player, and if you status something with Spore or Nuzzle, you might not get any hazards at all.
Also, Smeargle has to dedicate one of those four fabled slots to Magic Coat or it gets boned very badly by opposing Deo-S / Greninja. Unless you can fit both Taunt AND Magic Coat onto the same set, you're set-up bait for anything with Substitute (like Hypnosis Mega Gengar or SubDD Mega Salamence for example), which can and will lead if they see their opponent has a Smeargle on their team.
Smash Pass is not very good in a metagame where Lugia and specially defensive Primal Groudon are everywhere, not to mention prankster Thunder Wave from Klefki.
You might want to provide a counterargument (or any evidence whatsoever) of Smeargle's viability in Ubers if you want it to be revisited so badly. Sorry. (insert smiley face here)