Yes, this. There's no benefit to disabling link-local addressing, and
doing so can definitely break other IPv6 features. I've never seen an
explicitly-configured link-local address before, but I'd be really
surprised if it worked as a replacement for the
automatically-generated link-local address.
Manually configured link local adresses are quite common on routers.
And there is no reason, why it should not work, but having simpler
addresses on gateways can make some sense.
After all, where is the difference between a random, a RFC7217 stable
private or manual address?
To emphasise it again: It is not about disabling link local addressing,
that is not, what the stanza does, it is about optionally disabling
_auto_configuration.
