It seems to me, at least as far as my Google Autocompletes and general beginning linux searches, that many people who are new to linux are searching "problem $x ubuntu" not "problem $x linux."

That's just my anecdotal evidence, Linux, when it is adopted by new people seem to run Ubuntu and aren't as much aware of other distros, I for one don't know much about Arc or Redhat or too much about how they differ.