Oh ok, so people don't make the difference between a mobile phone and a computer. That is also why they don't know how to use a TV because it's not like a smartphone, right ?
That was a very bad idea from the very start. But it's the motto Gnome 3 was built on... I agree with the initial comment, Human-Computer Interraction SCIENCE went down the toilet drain to be replaced with so called UI/UX "experts"
The lock screen is weird, though, I agree. The newer (blurry background) one is better than the old one with the tedious swipe animation, but really could use a persistent "do this to unlock" prompt / button, because many people just aren't comfortable poking their computer unless they know what it is going to do. A lot of modern UI design unfortunately forgets that.
For what it's worth, the original design for GNOME's current lock screen involved bridging the gap between it and the login / switch user screen, which _would_ involve some more UI elements, but the actual implementation must have stalled somewhere.