Wicked Blow in comparison to other offensive moves is not that insane, it has 75 bp and always crits (for an effective 112.5 base BP, as well as ignoring stat changes).
It is strictly weaker than other powerful moves that have had acceptable power levels in the past, such as V-Create, Eruption, Water Spout, Boomburst, Draco Meteor and a ton of other widely used moves like High Jump Kick, Close Combat, Brave Bird, etc.
The difference between banning offensive moves to status moves is that some offensive moves are objectively better than other offensive moves, obviously Wicked Blow has use cases where it's a better move than these, but for base level damage, Close Combat is actually better for Urshifu to click than Wicked Blow, simply by doing more damage.
Additionally, Base Power is obviously going to be entirely relative to the pokemon's base stats. Obviously a mon like smeargle isn't going to be as strong using Wicked Blow as Urshifu-S is. There is a debate to be had as to when BP becomes too high, V-Create was seen as generally acceptable due to the drawbacks, but a move like Last Respects and even Rage Fist hit up to 300 and 350 base power respectively.
Ultimately I'm not entirely sure when we can say an offensive move becomes inherently broken, I'm just pretty sure Wicked Blow doesn't tread that line.
You can distinguish Wicked Blow and moves like Last Respects and Rage Fist but this isn't how Smogon decides to ban the move or Pokemon that learn the move. They look at whether some or all Pokemon with the move are broken. You put Last Respects and Rage Fist in the same category, but Rage Fist is not banned because Primeape learns it and is not broken. So Last Respects would not be banned after home if Chansey or Blissey learned it, and shed tail would not be banned if some terrible ZU Pokemon learned it and they're weren't good in OU. They ban the move or the Pokemon depending on what Pokemon learn them. This takes priority over the power and capabilities of the move.