Actually I didn't reference any decline in quality but in some locales, like Scotland where I'm from, you're absolutely right. Tennent's lager is now the most popular, it is not good. Where I am currently the most popular beer is between two lagers/ležáky - in western Czech Republic ("Bohemia" aka Čechy) the most popular beer is Pilsner Urquell, and in Moravia, where I live, it's Radegast - both higher quality beers. So it depends, but occasionally where I live allows me a very minor flex of "I can walk into most pubs and get spectacular ležák :)