When there is a raging thunderstorm and turbulence in the sky and you're flying at 32k feet, it is really a bad idea to climb over the thunderstorm to elevate to 38k feet, because while the plane is climbing, it is at an angle and at that speed, and still within the turbulent clouds, it can easily tilt over and stall. Besides, the higher you go, the chance of ice crystals forming and disrupting your instruments becomes higher. Clearly, the safe manoeuvre is to divert your route away from the thunderstorm at the same altitude, because one cannot out-climb a thunderstorm, which is known to form all the way to 55k feet and some even to 90k feet.