> I don't want to be a brat, but what is the possible overlap between people caring to use Tor (for whatever reason) and people using Windows 10 as the host OS ?

Journalists.

There are many journalists who need to cover sensitive topics, who are not particularly technically literate. They need to be able to buy a system off the shelf, do some minimal and easy amount of installation of privacy protection, and be reasonably confident that it will work and they will not be outing their sources to whatever particular despot is listing in.

Of course, Tails is a better solution for that. But in terms of being able to allow them to do their job as easily as possible, it would be preferable for them to be able to install the Tor browser bundle on their existing OS rather than having to learn an entirely new one (and possibly dual boot in order to run some Windows-only software, and not keep it isolated well enough and thus leak information accidentally).

It apparently took a while to teach Glen Greenwald enough of how to use Tor and GPG in order for Snowden to be able to communicate with him. We need to make this process easier, not harder.