I like fully qualifying domain names (like x.y. in your example) and it’s funny how many sites break when you do this
Wait, really? Could you share some examples? Why would they break for a FQDN. Wouldn’t that mean that the root servers aren’t configured correctly for that TLD?
I'm not sure exactly why things break, but as an example: fully-qualifying youtube.com (to youtube.com.) used to break the code that displayed the ads and you could watch ad-free