Meh, not really. The same way I could claim that yours is also just one anecdote. Otherwise we would be in the business of comparing how grand an anecdote we each can come up with.
But how about we add more anecdotes from other people?
You will find a lot of posts online, if you search for something like: "windows volume mixer too loud". For example:
[1]: https://old.reddit.com/r/Windows10/comments/lfi6yr/default_s...
[2]: https://old.reddit.com/r/techsupport/comments/e7j44w/minimum... (ooops, this person even mentions the 5% like I did, haha)
[3]: https://superuser.com/questions/1760843/how-do-i-make-the-wi...
[4]: https://superuser.com/questions/432040/how-do-i-lower-the-ha... (yep, juuust like I remember, even back to Windows XP this issue goes)
As another data point, one friend of mine bought an external audio interface, because of these and other annoyances in Windows and now regulates the volume using that.
