That is a particularly out of context and uncharitable take on that sentence. I have seen no announcements or discussion about systemd-resolved moving into ignoring DHCP, that is simply a comment from one of the maintainers expressing their opinion about the privacy argument. Other quotes from that same post that make his stance on when to use the fallback pretty clear:
> We use the fallback only as ultimate fallback, when the other option is to not work at all.
> we only did that in case no better DNS configuration was available, i.e. as last resort, one step before giving up entirely