An Overwatch player landed a ridiculous Deadeye ultimate for a complete team wipe. There is nothing sexier than a 6-man Deadeye ultimate, and any McCree main can tell you how hard this is to pull off.
With the amount of shields, barriers, and objects to hide behind, landing any type of beneficial ultimate can be difficult. That's why you always look for a flanking opportunity.
The Reddit post showed how effective a good flanking McCree can be when the enemy is too distracted on the payload. Whenever a McCree is ulting, the first thing players need to do is find where he is using the ultimate from.
That's where you can feel the panic in the enemy team, as the longer it takes to find the McCree, the better chance you'll die.
Blizzard seems to be back from the holiday break and back to developing Overwatch since developers have been communicating with the populace again. The community saw Overwatch developer Josh Noh talk about "power creeping" as well as Blizzard's balance philosophy.