Why would the easy part matter? The reason it’s done is because it’s easier :-/
Or for some who want to avoid an annoying mutation, rather than difficulty - eg last week’s Tax Day. Brutal on that was easy enough to do even with level<15 Swann & Karax separately, on pure def. [ Swann needs Multi-SCV Construction from level 8, and optionally lvl11’s structure life & turret speed increases. Karax needs insta Pylons, etc. from level 11. ] Fewer units and structures to command nearly negates Micro Transactions.
Fair enough 