[Izkata]

I'm guessing verbosity? It also reads like they don't know why pathlib exists and assume they were created at the same time.

os.path came first, often works by poking the filesystem directly even when it doesn't seem like it needs to (vague memory, not completely certain), and I believe has os-specific quirks (so code won't necessarily work without changes).

pathlib was created later as a pure-python implementation that allows for manipulation paths without touching the filsystem except when you explicitly tell it to. Because it's also pure python I don't think it has any os-specific quirks either, but I haven't explored it in depth. Code should work across operating systems without changes.

I think I also remember at one point people talking about completely replacing os.path with pathlib, or at least gutting os.path to the essentials that wouldn't work as part of pathlib.