Wiping the WhatsApp chat history on the old phone before giving it to a new owner is also much more important. It often contains highly embarrassing or even incriminating details.
In ecology, it's rare to species compete to extinction or exclusion from a niche. It's much more common to observe segmentation. It's a lower energy state for birds to mate at different times, eat leaves from different parts of the same tree, etc., dividing the resources of their niche among themselves, than to force each other out of the niche completely.
The situation is analogous. I'm sure they'd destroy each other if they could, but it's obviously not happening right now. It's much easier to say, you can have your current users, we'll have ours, and we'll focus our energy on capturing emerging markets. Which is why you see them racing to provide free internet to developing countries and such.
Don't ask me what's leading WhatsApp's legal department to believe that this feature doesn't comply with German privacy laws. It's quite puzzling. (I would've rather expected a feature like this to be mandated by EU laws.)
As of now, there's no non-hacky way of exporting chats for German users. (Hacky ways include: dubious third-party software, copying each message individually, taking screenshots.)
The net effect is that if you're switching you have to redo 2fa for all accounts where you haven't separately backed up your TOTP codes.