Okay. Original person this whole thread spawned from. I think you all went down the rabbit hole of "what's an advert" and lost the entire point of my comment which is lack of choice.
But before I address that choice thing let's address the "Ads" of Linux as you would call it. The "Featured" apps in a lot of software managers for Linux are selections that come from folks who manage the distro wanting to ensure that people know that "Linux can do that stuff that Windows can". The "Feature" is not there to promote Dropbox and pray get some money, it's there to point out to people "we can do that here as well, just FYI."
So you may feel that the featured in the software managers is "ad" but you can ask the folks who run the distro how they arrived at what's there and pretty much every case it's so they can show that the distro has some feature parity with what people are expecting. Now you do mention Firefox and they are indeed hawking their own product. Interestingly, Mozilla maintains a page about just this thing. And it's come up time and time again in mailinglists. Distro builders absolutely have the option to disable this in their repo, but by default build, it's allowed and default options is how a lot of distros choose build the package. And it's this later part that leads me to the point of my original comment.
CHOICE. Long story short because I feel I've already made this comment pretty long. You don't get choice in Windows. There's not some magic build that you can use to do away with all that Candy Crush and what not and still be this side of the TOS for the OS. And for Linux there is choice. It's less about ads and more about "do you get a say in any of this?" With pretty much every Linux distro, you always have the option to become a contributor in some manner. (As an aside) This is actually the friction that a lot folks talk about with how RedHat and the Fedora project have been doing things lately. They're sort of removing this option for the general public to have a line of commentary into the project. It's a bit more complicated than that, but even with the notions that they're toying with, it's been met with pretty strong reactions against what they're doing. And lots of distros have pointed out, that they are going to be doing the opposite of what RedHat is doing going forward on that front. (but I digress)
But that all said, looking at Windows. You don't get a say in the build process. There's not an option for you to rebuild the software stack to your liking for distribution between your machines. There's what the SKU offers and then there's just finding some other OS. And yes, that's not ignoring that enterprise Windows allows pretty much all of these things to not be a thing via group policy objects in the active directory, but it still sticks to the core aspect of only if your SKU offers that option and you need to use that SKU in accordance with the TOS for that SKU. Those are your options. That's the thing and while I'm sure the debate about "what constitutes an ad or not" is a noble one to have, I think you all lost the entire point of my original comment to debate this point that's not really a point that anyone was making to begin with. And also your view on that point of "what's an ad" is poorly informed from the Linux distro makers perspective. There's a need to point out to users coming from Windows or Mac and trying "Linux" for the first time that "we can do that too". That's distinctly different from Microsoft's goal of letting you know that you too can sign up for OneDrive.