It's not about the level of knowledge of the user at all, like... at all!!!
My folks use linux and wouldn't want to turn back to pay-to-be-spied-upon-warez at all, so are a lot of others. Ever more companies are switching to open source, because it delivers something that is very important: security. Not only data security, but also the knowledge that you'll be able to do the stuff you need to do as a company going forward. You won't be locked out of any means of production if some company decides that all of a sudden you're a minority that doesn't need a software update, or that the price has gone up so much that you have to start laying off people to finance the bloody software. These things are happening, and companies are learning that these things are happening, and that they are a serious threat.
The distinction between people that just want windows like it comes on their PC when they buy it online or at the supermarket, and just watch all of the dweeps on youtube sing the highest notes about Adobe or whatever mediocre commercial crapware that looks great IF it works as it should (and I use all of those things, I do know that they are far less reliable and break and destroy work regularly because they're not of a quality level that warrants a 140 EUR pricetag per user per year and to have your content held hostage at the same time, and to be honest, I pay commercial linux SLA's which are far more expensive than that, it's not about the cost as such, it's about what you actually get for the money. When I pay several hundreds of EUR per month for linux support that is 100% worth it, even though there are plenty of very linux qualified people running around here, that means that there is actual profit in that, or I wouldn't do it. The only thing I can say for Adobe and Microsoft and other commercial closed source warez (and that does include all of the Google crap and the Valve crap, which might be based on linux, but is not open source and is not of open source quality!), is that it sucks for the price. So Windows 10 is free to upgrade to... great, what about all of the man hours that have been lost in having to debug Windows 10 systems every single week since W10 was released? Missing drivers, missing functionality, missing everything, bugs all around... and it's been in beta for a whole fucking year! Face it, when Steven Sinofski was at Microsoft, and he got the assignment to fix Vista, they did a remarkable job with W7. Then he again did a remarkable job with W8 as far as the technical backend is concerned. So they fired him and reversed a lot of the technical benefits of W8/W8.1... that's all they did... to achieve what exactly... that every new device they sell still has the metro GUI because they're all touch devices and not usable with a start button? No wonder that Soma now also left after 27 years at MS... he was catching all the heat from devs on technet, from people that actually understand the crap that's piling up...
Your distinction is based on user skill. That's not correct, because there are skilled people, skilled at linux, that still use Windows for what it is good for, as a software console, as an entertainment system. You're assuming that skilled people don't use consumer entertainment devices. Your assumption is wrong. Of course they do!
The people that use commercial closed source solutions are not less skilled than others, they are just being consumers. Because that's what it is, commercial closed source software is not enterprise-grade, it doesn't offer a real opportunity to grow above and beyond, it's limiting, it's easy, it's prechewed, it's dumbed down, it's pre-configured, it's "don't think, we'll think for you"... and that's perfectly OK, if you know when to stop when it matters. The problem is that many people are overconsuming because of the "geek" trend. Everybody needs to be a computer wizz or a nerd or whatever... and they try to buy something to get there... not going to happen, they're just going to be out of money.
There is no "casual user". There is only a consumer and a professional user. Professional users are those that want to make money with the assets they invest in. Consumers don't care, they just want to spend money and get entertainment in return. That's why Windows X is so "gamified", that's why Android is so "gamified"... it's not about what it can and can't do, it's about entertainment, about interactive entertainment, internet-based entertainment for extremely bored people, that can buy some stuff, go on youtube, see linus sebastian rave about it, feel like they belong, buy something more that is even "higher end", etc... pure consumption and entertainment.
On the other end, if you want to get something done, and you want to stay ahead of the competition, and you want a balanced budget with a company that has employees that are real people with real lives and children to feed... that's where the entertainment stops, and where common sense starts... and that's where commercial closed source software is not justified any more, because it's dangerous and not productive enough. That's when open source everything becomes invaluable. Even for users that are not skilled in IT: secretaries, technicians, stock managers, etc... once you actually use what a fully open and unlimited system can really accomplish, they all benefit.