Self Analysis during games?

So it was only until recently that I discovered that it was completely legal to use the self analysis icon during games. For me this made the calculating and running through potential lines much much easier than simply trying to visualise the moves only in my head as I was actually able to play each possible move out on the separate board.

Anyway pleased as I was that I was able to use this to my advantage I was also surprised that this was even allowed at all, as I kind of thought one of the key concepts of chess was how far in your mind you were able to calculate, (without any help) and also I wonder if when always using this tool ones play at over the board games would suffer. Should I even be allowed, personally I'd say no. Just my thoughts.

Ah I see, thank you for the insight!