Mortal Kombat always had a plot, though. It was one of the ways in which they tried to differentiate themselves from Street Fighter, which had no plot other than ethnic stereotypes who like to fight and end up fighting Pol Pot, who has somehow acquired super powers.
I think sometime after MK established it's lore via it's comics, tv series and movies during the 90's, Capcom tried to do the same via the anime SF movie and their failed live action attempt, but outside of those, they haven't really gone as hard as MK has with it's media MK lore over the years.
SF is also trying to tell lore stories via in-game cutscenes and openings, but they aren't nearly as heavy as MK is now with their plots and general lore (to Capcom it's mostly about fine tuned fighting and combos/esports, than it is keeping up with MK's lore).
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