I am of the opinion that Canonical does in fact do a lot for Linux, and that this should be appreciated more. Sure, its contributions are not of the technical sort; I have seen the statistic before that Canonical only contributes to 1% of GNOME's development (despite Ubuntu being very much a GNOME-centric distribution; the primary contributors are Red Hat, Novell, and volunteers). The statistics are similar with regard to contributions to the Linux kernel.
But really, the whole argument is undermined by the very first sentence itself:
Ask anyone which GNU/Linux distribution one should recommend to would-be users and the answer is generally always one word: Ubuntu.They have made Ubuntu the most popular Linux distribution among newbies and have introduced Linux to the masses. Isn't that enough?