In what sense has it ground to a halt? Eight amendments have been ratified in the past 100 years. I think some people are taking a very short-term view here and lack a historical perspective.
Let's see how those other countries are doing 100 years from now.
A government structure that changes isn’t inherently bad. The US has gone through multiple iterations just by reinterpreting a document. Other countries tend to be a bit more explicit in this.
The US in 2026 operates fundamentally differently than in 1910, and both are unrecognizable to 1801.
The document was written when there were 13 states, and at best, appetite for a mere handful of others to join. For example, the degree of the weaponization of state-carving in the mid-19th century wasn’t in the cards. A 26 member upper legislature operates substantially different than one comprised of 100 members.