>>508247521. Smogon doesn't actually ban all that much despite what seething competetivelets might tell you
2. They don't want to completely change old metas. Snorlax is THE central pillar of Gen 2
3. There was a Snorlax-less alt-meta of Gen 2. It was even worse than when Snorlax was available since Snorlax kept a lot of broken Pokemon in check
4. Banning Snorlax would necessitate a cascade of new bans as Pokemon like Raikou, Zapdos, Cloyster, and Gengar suddenly become overpowered without their biggest counter around
5. The boomers who still play Gen 2 OU and its average 120 turn games don't want Snorlax banned because they like the meta as it is, and banning Snorlax would drastically alter a 2 decade old meta.
IIRC, the only time they drastically altered a meta after it was long gone was Gen 4 OU where they allowed Latias into OU and banned Arena Trap and Baton Pass. Most of that was voted on by the Gen 4 OU playerbase, and Arena Trap and Baton Pass got the axe in most generations (except Gen 3, IIRC)