Some individuals in the Linux community regularly criticize Canonical for "not playing along well with others" and taking Ubuntu in directions that go against "the community's wishes." I think those individuals are misguided. Canonical does try to collaborate with other projects and distributions. It's just that such collaboration is not the company's priority.
Canonical's priority, as best as I can judge, is to make Ubuntu the world's leading Linux distribution for desktops and other platforms -- cloud, tablet, phone, etc. So they will use whatever F/LOSS code works best to achieve this goal, regardless of whether it's internally or externally developed. They are not letting 'ego' and 'pride' get in the way of achieving their goal.
If using systemd will help them achieve their goal more than using upstart, they will use systemd. Ditto for Unity versus Gnome, and for Mir versus Wayland. For them, it's not about "winning the argument," but about "winning the #1 spot."