Microsoft flamed out of the mobile OS space precisely because they insisted that Windows not fork, but be identical software running on all devices.
So now, there is no such thing as a windows phone, but every time I wake up my computer I see a vestigial lock screen that I have to dismiss before I log in.
They designed their phones like a company entitled to 85% of the market share. Something tells me they're not going to reform just to capture that mobile game space.
I have never seen an ad on my lock screen. Possibly because of all the stuff I have disabled and the fact that I use windows 10. I have some questions.
What does the login screen have to do with mobile? They've had them since at least Windows 95 (I forget if 3.1 had one), and they've been evolving every release.
If you mean the screen before the login, that's been around since at least Windows 95 too, though it didn't used to be default and required you to press Ctrl+alt+del to dismiss (which before win95 would reboot your computer)