Where does the "Smogon doesn't want you to use your favorites" mindset originate from? Smogon wanting you to use your favorites is precisely why the tiering system exists in the first place. Nobody wants to pit their Illumise against a standard OU team.

Like, obviously if you just mindlessly stick your favorites on a team without trying to make them work together you're not going to do well. But it's not like Smogon cares if you do well or not.

And who are we referring to when we say "Smogon", anyway? The leaders? The community? The twelve-year-old who got upset he lost to a Crobat?

Is it just the fact that Smogon has optimal sets on their Pokedex, meaning that they think every Pokemon should only do one thing, or something? Because, well, yeah, they analyze what a Pokemon's strengths and weaknesses are for the format and recommend sets that can do the most. Like, Azumarill has Huge Power anda great STAB + movepool to use that with, so a high Attack and HP will work well with that bulk and typing allowing it to take a lot of hits. To abuse that high Attack, Waterfall and Play Rough are almost mandatory. Some Grass-types can wall the STAB combo, so naturally Knock Off or Superpower are going to be the recommended coverage moves. Then Azumarill is pretty slow, so Aqua Jet is a necessity. Thus a set for Azumarill could be: Adamant, Choice Band, Waterfall/Play Rough/Knock Off/Aqua Jet, maximize HP and Attack, and invest in some Speed to outspeed Clefable or maybe uninvested Rotom-Wash.

"Smogon", whoever that is referring to, isn't going to get angry that you're using a specially defensive Azumarill with Water Pulse and Rock Smash.

I really don't understand where this mindset comes from. Please, could somebody who believes this explain it to me?