19 states have “no more changing the clocks” laws passed, but aren’t allowed to do so without approval of the federal government?
It’s pretty obvious you can just do what you want these days, consequences are trivial to non-existent, so why don’t we just not change our clocks? (or change them and not change them back, whatever floats your boat)
Time zones were originally mandated for the sake of railroads: before trains each town used its own local time, and each locality refused to change their clocks to match anyone else’s. So time zones were set by the federal government because there was little chance that every town in the country would reach a consensus otherwise.
When DST was introduced much later, time zones were already an accepted thing—so the federal government gave states the discretion to adopt DST or not. But they have to take it or leave it: they can’t make it year-round because that would effectively move them to a different time zone, which is still the prerogative of the federal government.