DBus (the software, rather than the protocol) isn't required on Linux anymore than it is on OpenBSD. It's required by the Plasma and GNOME desktop environments, most KDE and GNOME applications, and any other desktop environments or applications that want to use it.

It's also cross-platform, and runs natively on OpenBSD, NetBSD, and FreeBSD. It does not leverage a compatibility layer, and depending on it is in no way comparable to requiring an emulation layer like WINE.