And there is definitely a feeling that Americans don't like you insulting their country, as shown by your replies on this thread
OP, every American I know (including myself) will criticise the US's many faults at great length, and will happily self-deprecate. That is different from smiling benignly while people from other nations repeat misinformation. There is a lot of real anti-American feeling on Mumsnet, which can be pretty hurtful. Many things which you and others have said are just not true- for instance, flag burning is not illegal, but protected by the constitution.
I realise that there are also a lot of insular, small-minded Americans who want to "Make America great again".
Similarly there are a lot of narrow minded British people, so I don't agree with your statement:
Any Brit will join in with you in mocking Britain as will the French, generally. If you were living in Germany (for instance) and a group of Germans started repeating untrue things about English people, the NHS, etc, I am not sure that every English expat would join in in a good humoured manner.
I have lived in England for 18 years and love so much about your wonderful country, but I don't think the narrow minded and misinformed attitudes people have towards foreign ways of doing things is anything to be proud of.