> The USA has had an uninterrupted system of government since 1789.

Sort of. We had a civil war. We had a second founding. Then we had violent overthrowing of the reconstruction governments in the south. It has been less than 100 years since the US has provided the franchise to everybody, and even then this is a bit questionable.

Instead of constitutional amendments we get aggressive reinterpretation of the text by politically motivated efforts to change the courts. Despite no change to the constitution itself we've created criminal immunity for presidents and overturned interpretations regarding separation of powers than have been in place for a century.