Well in my index/bootstrap file I do not use a namespace.
Normally I would load my application in that file without creating a function in there.
And yes i meant if you have the same class but different namespace it works fine but if you had 2 classes with same namespace it would conflict in some way I guess.
( I never use the same class in the index file a second time so not sure what would happen.)
Please forgive me for the confusion but I am used to use composers autoloader.