I still fail to see why we need DBUS in kernel, so please correct me and clear my lack of understanding. It is claimed userspace dbus performance is bad, but pe

I still fail to see why we need DBUS in kernel, so please correct me and clear my lack of understanding. It is claimed userspace dbus performance is bad, but people want to use it in a much larger scale, so what I deduce from that is there is nobody using dbus on that scale right now, since its performance sucks. Reason for getting kdbus into kernel, and not a generic ipc but specifically kdbus, is because user space that depends on dbus will continue to work with kdbus. What I still don't understand is, what is the point of keeping compatibility of currently non-existing userspace, if software that depend on dbus right now doesn't need performance enhancements and can just keep using regular dbus, and software that need high performance bus doesn't even use dbus since it's slow? Under these circumstances, why they insist on making kdbus strictly a dbus implementation but not a more generic ipc mechanism?