Hi woltej1 ,
That used to be the case once upon a time , but not anymore these days there are quite a few cases where the motherboard lays flat
example - the coolermaster Haf xb , i think at the end of the day it is so that you can place all your components in a case without having the case extremely wide , most people dont want to take a a lot of room on their desk , going verticaly solves this issue.