Maybe? I can't compare 50% to 100 billion. If your computer crashed every 100 billion instructions that would be a problem. If it crashed every other instruction, that would be very slightly more (or the same amount) of a problem.

The point is that if you have a function call, you have the opportunity for a bug/ failure. Networks don't change that - you have the opportunity for a bug/ failure. The major difference is that services have stronger failure isolation.