You are not crazy! However cancellation is an advanced topic. It requires some experience to get it right - and even to understand why it's required at all.

Most people will not see the need for cancellation - until they either need to implement a deadline timeout later on, or run into the problem that lots of outdated tasks take up their memory. Those things can come up years after the inital program had been written.

It's also not purely a Go thing. E.g. in Java thread interruptions are also barely handled correct. Or CancellationTokens in C#.