You can’t get 60% of Americans to agree on anything politically, not in a large population sample anyway.

That number was specifically chosen so that nothing in the future would ever pass.

There’s a reason they chose that 60% figure in the amendment proposal: if you don’t really think about it, it seems reasonable (it’s not even 2/3rds!) But in reality, in the country’s currently fractured political climate, getting to 60% is near impossible. Hell, if a Presidential candidate carries a state with 55% it’s considered a crushing defeat, so 60 is a crazy high bar.