alt Hacker NewsOverdrafting accounts or negative balance in a bank account has nothing to do with what I was talking about.
A negative number in my comment is just the "from" part of a flow.
Just like in engineering, if you consider a dam, you can talk about the outflow as "-100 L/min" to indicate that the dam looses 100 litres per minute, for instance.
That does not mean that the litres of water anywhere ever becomes negative.
You do not say using negative numbers in engineering is a hack just because some numbers (like volume of water in the dam) is constrained to be positive.
In accounting one instead talks about the dam being debited 100 L and the electric plant being credited 100 L. That is basically just a different way of spelling "minus". It is the same thing just using different words.
And it is of course entirely possible to overdraft an account by debiting too much and get an invalid state entirely without negative numbers.
Negative numbers are actually a "hack" (or useful invention) in engineering and everywhere else too. They don't actually "exist", it is an abstraction similar to imaginary numbers and real numbers. But all of these are useful.
Negative numbers are a hack in the sense that they can be confusing, and it's easy to make mistakes with them. For example, I would interpret "-100 L/min outflow" as an indirect equivalent of "100 L/min inflow". To avoid confusion, you could drop terms "inflow" and "outflow" completely and talk about "-100 L/min (net) flow". Or you could separate the type and the magnitude of the flow.