Well, to speak on FF13's behalf...
Button mashing cannot be implemented as in fighting and action games.
For the most part, yes, it is as easy x,x,x,x,x,x,x *Victory fanfare*
In FF12 tho, you really don't do anything lol

In FF13, without spoiling, you can just press x,x,x,x for the first half, the second half however, increases the difficulty and just the simplicity of x,x,x,x,x will get you killed. Hope I'm answering you how you expected.