Yes, but now the authors don't need to manually decide to also share their research elsewhere - something they've (in many, but not all, disciplines) been train

Yes, but now the authors don't need to manually decide to also share their research elsewhere - something they've (in many, but not all, disciplines) been trained not to do as publishers traditionally wouldn't allow it. The fuss is about publication and approval being seen as linked in the academic hivemind. Even if you're able to see them as separate steps yourself, that doesn't mean that the academic world at large sees them as such, so if this fails to gain widespread acceptance, the reputation of eLife-the-journal might suffer, and having been published there will no longer look as good on your CV as it currently does.