For example my own (US) has a political system basically frozen in amber from a time before many of the political and policy challenges of our day were not even thought of yet. And they did their best to create a change mechanism, but I think anyone being truly fair of any political persuasion has to admit that while it has prevented nearly every harmful extremist constitutional amendment (I'd say Prohibition is the main one that sneaked in), it has proven to, within the lifetimes of most living Americans, be so hard to attain as to set the status quo in stone.
The framers didn't realize that most changes would be blocked by at least one party, out of fear that it would advantage the other guys. Same reason we stopped admitting states before letting Puerto Rico in, an absolutely absurd situation.