It’s only fun if you want people to know you voted. Not everyone does.

From a IS centric POV, are there communities where voting is looked down upon?

I was mostly thinking people in coercive relationships.

But in terms of communities it might be that voting is looked down upon for certain members of that community not the community as a whole.

In broader terms while marking people who have voted may not reveal who they voted for it does reveal that they did vote. This is less private than the election authorities maintaining the record of who has voted.