“Urban myth” kind of suggests that it was never true, which isn't the case, though it is one of those out-dated truths that doesn't go away quickly.

At one time Ubuntu as the easiest distro to get certain hardware running with because of the inclusion of proprietary drivers & codecs (unlike its Debian parent, amongst others, at least at the time) and making them easy, near-automatic, to configure compared to others that did include them. The distinction is long gone, and Ubuntu is simply one of several (many) good ones in that regard, but the perception that others have not long since caught up persists.