You are missing the part where the user manual and the systemd new features announcement state that the Desktop Bus API is systemd-resolved's "native, fully-fea

You are missing the part where the user manual and the systemd new features announcement state that the Desktop Bus API is systemd-resolved's "native, fully-featured API"; and describe the GNU C library NSS API and the DNS APIs as limited functionality APIs, whose avoidance by applications is "strongly recommended" in the case of the latter.