I would start by making a distinction between owning the hardware and having unrestricted control over the operating system.
You have outright purchased and therefore own the physical device, including its processor, RAM, storage and other hardware components. However, ownership of the hardware does not necessarily mean ownership of the operating system or an unconditional right to have every application, process or operation execute without restriction.
macOS is Apple's proprietary operating system, and Apple determines, to a certain extent, what it permits, what warnings it displays and what security mechanisms it enforces. By purchasing a Mac, you acquire the right to use macOS under Apple's applicable licence terms, but you do not acquire complete control over Apple's software or its security policies.
That said, there is a legitimate distinction between protecting users from malicious activity and obstructing legitimate software development.
If you have deliberately chosen to develop an Electron-based ad blocker on a high-specification Mac mini for application development and security testing, it is reasonable to expect the operating system to provide a clear explanation of what it is blocking and a documented way to configure the relevant security controls where permitted.
A warning that "Malicious instructions can look legitimate and are commonly provided in websites, chat agents, apps, files and over the phone" may serve a useful purpose for less experienced users. However, repeatedly interrupting a developer's workflow without sufficient context can be frustrating, particularly when the activity is intentional and takes place in a controlled testing environment.
The answer, in my view, is not necessarily to disable every security feature, but to give the owner and administrator meaningful control over how those features operate. Developers should be able to understand the source of a restriction, distinguish an actual security threat from a false positive, and configure an appropriate development environment without having to fight opaque or unexplained operating-system behaviour.
Ultimately, buying the hardware does not guarantee unrestricted control over the software running on it. But that does not mean criticism of those restrictions is unwarranted. Security and user autonomy should not be treated as mutually exclusive.
And yes, I agree with the perspective put forth by @ John Galt
