Linux distros are a mix of mostly independent projects, there is no central authority telling them how it should be done and therefore inconsistency is inevitable. It applies to the command line too (looking at you "ps"). And yet, the parts that the distro vendor controls, usually the default desktop environment and settings screens are usually rather consistent.
For Windows, I don't think anyone complains about the fact that if you run an ancient Windows app, it looks like an ancient Windows app. In fact, backward compatibility has always been one of Microsoft strongest selling points. What people complain about is that Windows itself is inconsistent. Windows branded components, made and owned by Microsoft, included in the main OS with no alternative offered are inconsistent. The worst part is the control panel, it is a mess and they have no excuse, it is an unfinished job that shouldn't have been out of beta.
Many distros adds their own layers of complexity, which inevitably breaks during upgrades or adding packages from third-party repos.
Arch packages do very little extra usually, and often works more like if you install from source. So it's not always the fault of devs, and is why installing from source was/is a thing.
Bonus with Arch is Aur, one big repo with most open source software available from git.
For Windows, I don't think anyone complains about the fact that if you run an ancient Windows app, it looks like an ancient Windows app. In fact, backward compatibility has always been one of Microsoft strongest selling points. What people complain about is that Windows itself is inconsistent. Windows branded components, made and owned by Microsoft, included in the main OS with no alternative offered are inconsistent. The worst part is the control panel, it is a mess and they have no excuse, it is an unfinished job that shouldn't have been out of beta.