BIGGEST UPSET EVER or false ratings?

This is a live chess.com game between an 1200something rated player and an 1500something rated player.both players played thousands of games in this site..the game is without any big surprises,has a typical opening,both players avoid extreme risky moves...

The paradox here is that the weakiest(always typically)player wins comfortably...what's the wrong here?one explanation is that in bullet chess games players make more mistakes that we usually can't give any logical explanation-it just happens..The game was not so fast as someone might think..

The question here is:"should we care about ratings?do they tell the truth?how often?or is it just a typical way to count strengths,organise tournaments and give prizes?"..ok that was more than one question..