(Trip Advisor is arguably the world's largest travel website, and supports languages from all around the world, but they have banned all submissions in Welsh.
Allegedly, the ancient Celtic language, one of the oldest European languages with over half a million speakers in the UK, breaches their sites strict language guidelines. Trip Advisor said that they were unable to integrate Welsh into their moderation and review policies. In other words no one speaks Welsh there.
Surely some enterprising Welsh speaker could set up their own review site.)