> Treating DoS as affecting availability converts the issue into a "do I want to spend $X from a shakedown, or $Y to avoid being shaken down in the first place?"

> Then, "what happens when people find out I pay out on shakedowns?"

What do you mean? You pay to someone else than who did the DoS. You pay your way out of a DoS by throwing more resources at the problem, both in raw capacity and in network blocking capabilities. So how is that incentivising the attacker? Or did you mean some literal blackmailing??