if you get 3 tempi ahead it is the same as being a pawn ahead.
but being up tempi is fragile if you make pointless moves and your oppponent catches up suddenly you are no tempo ahead.
I think it means that if you are up tempo you must maintain the advantage you have.
yeah but in the hands of average players a pawn is verry fragile too. you can easily lose one.
so being up one tempo means nothing if you don't use it.
you have to develop and being one move ahead all the time. and use the knowledge that your opponent is behind.