[2019] GGG's confusion in new skill description: Cone and Wave isnt the same thing

You're assigning your own meaning to those terms which is not inherent in their definition.

Leaving aside that the correct term for this shape is a sector (a cone is exclusively a three-dimensional shape, not two-dimensional), since I've already lost the office fight for correct geometric terminology; areas in the game are defined by their shape -they frequently spread the damage to things in that shape out over time, and that doesn't change what the shape is.

Ice Nova's damage is still dealt a circular area, even though it doesn't deal all that damage at the same time, but spaces it out based on distance from the player.

The damage pattern of Ground Slam is directly equivalent to this skill - you seem to be trying to draw a distinction entirely based on visuals (the fact that the spikes at one end of the damage area are still visible at the same time as those at the other), which is not at all how anything in the game is or will be defined, because those have no bearing on the gameplay and indeed could be entirely different on a microtransaction version of the same skill. Both these skills deal damage to things in a sector cone shaped area, and both deal that damage at different times based on how far from the player each enemy is.

If I walk in a square pattern, it's not wrong to call that a square just because I wasn't at every point around the square at the same time.