Standing on pedals during group workout

Whenever I’ve done a group workout it appears every other rider stands on their pedals when we hit a hill while I am the only one who appears to be riding in a seated position.  To join the group I stood too even when not appropriate in that section of the workout.  I have since been told that this is not real, other riders avatars show them to be standing even when they really are sitting in their saddle. 

What was the rationale for adding this in the first place?  How does it add to the group dynamic to show you as the only rider sitting amongst a group of 50 riders?

I think the rationale is it makes it easier to spot your rider especially if you are all wearing the same kit. While you may see your rider sitting other people will see it standing.