Given what we now know about backmigration and intermixing (particularly with Denisovans), it's really not coherent to say any "out of" theory is the Truth.
Sure, modern homo sapiens outside of Africa are all descendants of a founding group that left Africa, but they are also descendants of hominids who returned to Africa from elsewhere as well as local hominid populations that had left Africa far earlier (like Neanderthals and Denisovans).
Out of Africa has meaningful consequences even if people mixed back in. For example our closest evolutionary cousins should barring evidence to the contrary also tend to hail from Africa as well.
It’s that kind of reasoning that makes it important to try and be accurate here. Not a fact in isolation but everything else that it implies.
Sure, modern homo sapiens outside of Africa are all descendants of a founding group that left Africa, but they are also descendants of hominids who returned to Africa from elsewhere as well as local hominid populations that had left Africa far earlier (like Neanderthals and Denisovans).