Range extender EVs made a lot more sense a decade a go when batteries were much more expensive, and fast chargers were not yet ubiquitous. Then range extenders were more affordable than EVs and could go to places EVs couldn't.
Now these EREVs are mostly luxury niche of big cars (where extra space taken by two power trains doesn't matter) for people who don't want to spend 20 minutes at rapid chargers on that yearly long trip they do. Or for people who live in some global warming ignoring backwater[1] that hasn't built out rapid charger yet.
[1] even China has ubiquitous fast charging network now
Now these EREVs are mostly luxury niche of big cars (where extra space taken by two power trains doesn't matter) for people who don't want to spend 20 minutes at rapid chargers on that yearly long trip they do. Or for people who live in some global warming ignoring backwater[1] that hasn't built out rapid charger yet.
[1] even China has ubiquitous fast charging network now