Perhaps your claim of fact is being ignored due to its highly dubious nature. That's a list of beers, not of brewers, and even on the first page we see multiple products from a single brewery in a few different cases. The list also appears to be somewhere between 126 and 150 items in length, unless they're making that annoying pagination mistake where you don't give any clue to the true length.

So what you've cited in support of your argument in fact militates pretty strongly against it, because a hundred or so breweries isn't a very large subset of all those in the UK - according to CAMRA, that's a total of 1424, which puts the fraction on your list somewhere around seven percent. That's a little strong for my taste, but still a good beer. It is also, one might dare say, a relative handful.