1.) It is the easiest game mode to master, and is great for weaker/newer players.
2.) It exists because it is better than the old 1v1 mode.
3.) Players who enjoy(ed)/play this mode include Ratburntro44, ace199212, Calleharmemark, Ratsmasher, maybe Joriom, myself, and several others.
However, Lopdo hates it, but not enough to hold to his word and remove it in 2.0.