>>40347435100 Special Surf hits pretty much nothing besides Rocks hard in Gen 1, it's not a particularly useful STAB when most of the meta is either Water-resistant or too specially bulky to care. Starmie sometimes gets away with it since it's ok for hitting Alakazam over and over during long wars of attrition, but Gyarados obviously doesn't have the recovery or Psychic typing to make that an option. A STAB that's worse than non-STAB Blizzard isn't all that good, certainly not compared to the Normal, Ice, and Psychic STABs that pretty much define the meta in Gen 1.
>and it ran special sets in gens 2 and 3It runs nothing in Gen 2 because nobody uses it. In Gen 3 the main sets are DD and CB, I don't think anybody actually uses a special set. Take the old Smogon analyses with a mountain of salt, most of them are very outdated.