While that’s true for mitigations, one system can be more secure than another by design
Things like an OS that’s designed with sandboxing, more clean codebase that’s auditable, permissions, … in mind is more secure than an OS that later adds them as an afterthought
Or at least if added later they should be done properly
iOS and Android are way more secure than Linux (And no Android isn’t just linux) cause they were designed in much later era with better security practices in mind
Even MacOS and Windows’s security are objectively better than linux’s even though they started with same security mindset, the problem is they are not open source