Oh I get it....you want to be a pedant.
If you want any discussion about Linux limited to the kernel, then say so. But a kernel is not an operating system.
If its not some amateurish log in screen (on its most popular distro BTW) its something else in the operating system that is a joke.
Or do you think users should now de-install the default log-in manager, install something that someone may have rolled in the bedroom and risks breaking the system? Because you know "Linux isn't Linux isn't Linux and can be any flavour you want" TM?
Another classic example of Linux wasting time people's time trying to get it to do RST* (Really Simple Things). Like a login manager that actually makes sense by default..
If you can't even use correct words to mean what you want to say why on earth should anyone waste their time reading your twaddle?
As for your issue with MDM, my kids don't seem to have a problem with it but if they did they'd do what anyone with an ounce of intelligence would do and report it as an issue to the vendor's support dept and ask for it to be changed.
It's amazing the effect good genes and a proper upbringing have on a person's intelligence and ability to help themselves.
Please do go on making yourself look like a tit, it's hilarious.