[At the very least, D.Va is a member of Overwatch he doesn't quite know as he does the others--so his insults would soon lose gravitas over how little he actually knew about the Starcraft-streaming mecha driver.]

'You guys'? There's only one Reaper, Miss Song.

As for the answer to that. It's only as fun as you make it.

Kids can't help but to get up in arms when someone insults them.