The only thing that makes me think it's not that simple is it seems like maybe the issue is with their coding and, specifically, calls to whatever database they're using. They've had to essentially turn off anything related to queries (any items, after map stats, literally all the matchmaking and stats for it like number of players) to that database.
Which means just scaling up servers for more players exacerbates that problem since you're only adding to the database hits, which is something they need to fix in their coding.
Admittedly, I don't know enough about how that works. Could they add more backend to their database server(s)? Maybe. I think they really didn't expect their game to get 20% of these numbers and just lazy coded it with that assumption without any room for scaling.
Whatever it is, it's not great for them. Gamers are fickle. This is incredibly bad PR and people won't forget it. A lot of people are going to move on, and likely ask for refunds.