Why can League after all these years still lock up your whole pc?

I can not comprehend why after all these years this issue still exists. Sometimes during the loading screen League just stops responding. But the real problem is that it Locks up your screen to the point where it is impossible switch the current window and therefor impossible to close the programm. This means you will have to restart your whole PC what if not realized soon enough will usually lead to a remake and you loosing your LP or even Promos.

Basically if you try to hit alt+tab you can change window, if you try pressing the exit button on league in the alt+tab menue nothing happens, if you press windows key+m nothing happens, if you only press windows key only the taskbar appears and if you rightclick league and chose close nothing happens, if you hit str+alt+del you are brought to the according menue but if you chose task-manager to maybe terminate the exe the task-manager is started but you are still locked in the league screen and therefor are not able to use it because of stated previous problems.

In my opinion it is just sloppy and a disgrace that this still exists and Leauge doesen't mange to handle a full screen like every other game out there. For me this used to happen about as often as somthing doesn't work as intended in the new clinent (worst example: it crashing during champ select) but since a few years Leauge never stopped responding for me in the loading screen so a assumed this was fixed. I guess I was naive.

Sorry for the rant but this is just stupid.