The implementation we have of this in OpenBSD is about 36,000 lines of code without the crypto. That's just the protocol. I can't think of one single piece of code that size and start to debug it. The Boeing 747 flight control deck has about 30,000 lines of code, separated into 12 independent modules. That's the right way to do things.
Systems get larger, but code still has to be broken up so the human mind can grasp it.
Most of the IDEs don't reduce complexity, they just help you manage it. To have something that works well, you have to reduce complexity.