There IS a special relationship between the MacBook and macOS but it is exactly the other way around. macOS is optimized to run well on the hardware that Apple chooses to put in the MacBook. The hardware itself? A 100% standardized package. 100% compatible with Windows, various Linux distributions and Unix derivatives including macOS.
A MacBook is just a PC, just like every other laptop on the market.
I don't know how you define a computer running well in a OS. Maybe my standards are different from yours. For me, a notebook runs well means:
1. performance: cpu, ram, disk i/o, network connection speed
2. comfort: keyboard, trackpad, screen, battery life, heat on c-side (keyboard side), fan noise
You point is correct on performance. As the hardware are standardized, there shouldn't be much differ, unless some extreme conditions, like overheating, happens.
You point is not correct if you consider comfort on "battery life, heat on c-side (keyboard side), fan noise". When you run Windows, MacBook air/pro always makes more fun noise, generates more heat and gets less of battery life, comparing to use the same MacBook air/pro in macOS.
You may argue that it is because macOS manages hardwares better than Windows. The comfort downside from macOS dues to Windows, not MacBook. However, from a buyer's point, he should consider if he could pay the same money or less, but still can get a alternative.
The answer is definitely yes. With the same money or even less, you can always find a better notebook with the same hardware performance and more comfort using Windows. Or saying, when running Windows, MacBook is not the one of best comfort.
That is my point.
I am not a Mac hater. I had 2 Mac mini(2011 and 2012), 1 Mac(iMac 5K 2014), 1 MacBook(MacBook Air 2013), 2 iPhones(iPhone 5 and iPhone 6s Plus, 2 iPads(iPad 2 and iPad mini 2). All of them were bought since 2012. Before that, I had been using Windows for 13 years. I am now a developer using Swift. I use Linux(on Server side, using remote control), Windows (on a separate PC, when I want to play games) and macOS (everyday use).