Nope, lets take a simple case
H -> T
H ->H
T ->T
T ->H
if i get heads in my first throw, what is the chance of getting heads again?
What you are thinking about is "what is the chance that in 2 throws I get 2 heads in a row?" that is 25%, but, as you see, after getting the first head, the second coin has 50% chances of getting another head
I don't understand how this analogy is related.
The original idea was showing that with enough enemies coming at you, crits can potentially be pretty likely. I don't think any one was talking about the chance of any specific one enemy getting a crit, but rather the chance of 1 or more enemies hitting a critical out of the twenty that tried.
So with the coins, I don't care if both are heads, the first or the second. I care if it ever hits the ground with Lincoln facing upwards, killing my character and forcing me to reset the chapter I've been playing for the past hour.