Not everything that runs on windows is proprietary I use a lot of open source software on Windows myself. Windows is also a lot easier to configure to run exactly the way I wanted to run and to be the OS I need it to be. It's extremely customizable and easy to control. It's also modifiable in many many more ways.
>Windows is strictly quite a bit less configurable than Linux.
I wish I could agree, but I just can't: the OP may be correct, depending on which Linux desktop environment he's talking about.
*My* Linux is indeed much more configurable than Windows, but I'm using KDE. However, that's only promoted by a few distros like openSUSE. Most users are going to get GNOME shoved in their faces whether they like it or not, and no, GNOME is *NOT* more configurable than Windows. GNOME needs to be used exactly as the GNOME devs want you to use it, because otherwise it'll just break on the next update. For many users who are not Linux experts, and perhaps use Linux at work where their IT departments only allow them to use GNOME, they think GNOME==Linux because that's what most distros push so strongly, so I can see why OP would make such a claim.
I think there are two factors that lead people to make statements like that. The first is a given: they're talking about configuring it as a user, not a developer. Obviously Linux can do whatever you want it to do if you build your own distro from source. But additionally, while Linux is also substantially configurable in userland, those configurations might not actually cover the cases people need. You can, for example, pick between GNOME, KDE, etc -- which, on a pedantic level, is "objectively" more customizable than Windows, where you have exactly one option. Yet, if the settings within all of the off-the-shelf GUI shells do not serve the use cases the settings of the single option on Windows does, users will have every reason to assert that, on a practical level, the degree of customizability is inferior and not sufficient for them.
The idea that KDE is not objectively more configurable, in every way, than Windows, is lunacy.
However, GNOME is completely the opposite; doing anything differently requires installing special extensions, which break every time an update happens. The devs do not want you changing it from their One True Vision for how a desktop should work (which, apparently, is almost identical to a tablet).
People who aren't Linux experts or long-time users may not even know about KDE, Xfce, etc., and just think that GNOME is the only way to use Linux. Most distros push it very strongly, and even in corporate environments it's pushed hard. My company uses Linux, but the IT department only supports GNOME; luckily I'm able to install KDE but I'm basically a reneage by doing so.
So if we're comparing Windows (which has only one DE, the Windows one), to GNOME (which for many users is synonymous with Linux), I'd say he's right: Windows is much more configurable and easy to customize.
Why the Linux world has gone this way, I honestly have no idea. It almost seems like a conspiracy.