Good example you posted tbh.Here is a clear example of "play" in a minimal sense. He slips, changes the direction of his boot, he enters the path of the ball and the ball changes course. If you are ultra comfortable with interpretations this might be a play. So I am happy to agree there is a case here.
You have an action
the ball is hit
the ball is affected
In the case of Alvarez there is no action, at best the ball scrapes his boot already planted there, following the same path.
Also the ref doesn't call it, because it's impossible to see, and the VAR who is not in jurisdiction makes the call for him.
Absolute fraud.
Mahrez touch is clearer than Alvarez slight touch. But it's still there, it's like offside, sometimes a toenail is offside sometimes a whole leg. There's no room for interpretation, it's either one touch or two touches, even if minimal.
Ref can easily just wait for VAR nowadays. No need to blow and guess if he didn't catch it, but all of us suspected there might have been two touches when watching it live. VAR just confirmed it.