What's "the obvious thing" largely depends on what you're used to.

Apple has labelled the key in the upper-right corner "delete" for the last 30 years. It deletes selected objects, or without selection letters or objects to the left of the cursor. In Terminal, it sends ASCII-127 (DEL), not ASCII-8 (BS), just like ancient DEC terminals.

Most PC vendors labelled the key in that position "backspace". Without selection it deletes letters or objects to the left of the cursor, and with selected objects it may or may not delete them. In most Windows and Linux terminals, it sends ASCII-127 (DEL), not ASCII-8 (BS).

Given all of this, it not at all obvious to me that the key should really be named "backspace" rather than "delete".

When 90% of the other computers on the planet do it differently?

I’m pretty sure that I can make some assumptions about what is going to be obvious to most based on that alone.

By that reasoning everything in Windows is obvious since 90% of the other computers on the planet run Windows. So why not just stick with Windows and stop complaining that things work differently on non-Windows computers.

That logic is perfectly sound. When something becomes ubiquitous it certainly does become the obvious thing to everybody. That's why in modern times it's more obvious for people to toast bread in a toaster and not in a frying pan like they might have done in the past.

Aside from that - explicitly having both Backspace and Delete is also obviously better than having only one of them and hiding the other beneath a multi-key shortcut.

You mistook pointing out a flaw for complaining though. I'm not complaining since I'm not stuck on a Mac. I keep one around for doing iOS things and for helping Mac users figure out how to do things.

Personally, I prefer to use a Linux desktop system that draws deeply from the Windows UI and currently that is Manjaro with XFCE. With that I get the best parts of Windows, I can customize it to do just about anything I want and it's even more stable than Mac or Windows.