Pixophir I'll simply never submit to that. The only reason I can imagine for myself is being in a job where this is necessary. Fortunately, I can choose my job :-)
Yes, it's easy to say that, but if you have a business you have to make concessions. It's hard to get actual numbers, but most cross-platform mobile games make the vast majority of their money on iOS. The percentage numbers can vary, but I have heard in the 80 - 90% range, in favor of Apple. You can see this developer released the numbers and only made 5% from Android.
There are a lot of reasons for this. Apple products are more expensive, meaning the users are typically more wealthy. Apple is very popular in developed countries, while Android is more popular in developing nations. Android has piracy, as well as alternative app stores with stolen content (Apple does too, but it is much much harder to do and is frequently shut down). Regardless of the reasons, if you want to make a mobile game, and it is your business, you have to be on iOS if you want any sort of revenue.
The issue on desktop is much less. macOS is a small market (slightly bigger than Linux, but not by much). And Macs typically don't have gaming GPUs and a lot of users are on laptops, meaning almost none of them game and couldn't even if they wanted to. So making a Windows only game is usually what developers do (and with Steam you can also target Linux with a Windows binary). However, in the spirit of cross-platform, I will want my game to be native on Windows, Linux, and macOS. Because excluding Mac users because of Apple's shady business practices is also kind of lowering yourself to their level. I would want everyone to play my game, and also as a business to have the most revenue possible. Even if Mac is only 10%, that could still be an extra 10% of whatever, with not too much effort.
Linux is only around 5% overall, however Linux users do game a lot and spend money on native Linux software, so I have seen developers claim that Linux sales were between 20 - 30% of the revenue, despite only being 5% of the desktop market. So for me it is about being inclusive, and not cutting off portions of the market because of my beliefs (this also gets into the thing I was saying about making compromises in the real world). It means more people can enjoy the content, more money for me, and is just generally a positive thing to do (in terms of showing people they can get away from Windows). So I can live with that.