That's a lot of snark for a reply to a post checking that I'd understood the situation correctly.
I'm aware that MacOS and Windows are different operating systems and so you need different compiles of the application, 30+ years in the IT/Computing industry, and still going, kinda makes that clear. The norm, however, for cross-platform application development for about 25 years now has been to use abstraction libraries so the same code is compiled for each platform, just using different libraries to abstract the application from the OS services, the developer only needs to think about the application they are writing, not the differences in the OSes they might run on. If your suppliers are telling you they need to code separately for each platform and aren't writing drivers or embedded code (and actually a lot of driver writers are using abstraction libraries these days) then they are ripping you off or need to give their development team a Vegas funeral.
This is the first time I can recall an application where you needed a different license depending on which desktop platform you were running it on for quite some time. It's kinda inherent in the language of software licenses, you're buying a license to run the code, not the code itself. This is why in most cases you can install the same application on more than one machine (same or different OS) and so long as you only run it on one machine at a time you're fine with a single user license.
The price point for Affinity is not that dissimilar to other packages with similar functionality from what I've seen, it's the same as I'd pay to upgrade PSP and about £25 less than the new cost of PSP. I think what you really mean is that 'Affinity isn't a rip off price like PhotoShop can afford to be due to its name recognition." The issue for me (and possibly the OP) is that wanting to run on both Windows and Mac is about convenience. Do I want to double my cost, and learn a new application, to avoid having to carry two laptops once in a while when I need to carry the Mac for some other reason, or do I only pay about the same and stick with the application I know but 4-5 times a year I'll have to carry my Windows laptop and my MacBook or put down my MacBook and go into the other room to get my Windows laptop.
I'll have to think about it.