Don't put to much into what you find in this forum and really many online sites, more often than not there is a bunch of people that just hate one anyone not like them self.
That being said it can be pretty jarring when one meets US tourist in Europe, not always but often they tend to be loud, act with a lot of entitlement and sort making as if what they see here is sort of like a Disneyworld ie. totally forgetting that Europe is ancient compared to the US and that for the most part we celebrate our history.
I have friends in the US and they are people I hold in high regard and while I did not list them, there is also a lot to like about the US. It is a shame that so many stateside know so little about the World outside the US and that even fewer seem willing to take inspiration from things that are done better than in the US.