As someone else pointed everyone is already on DST for approximately 65% of the year. This just removes the remaining 35%. Picking standard time would have been a much bigger change.
Ultimately, it's entirely arbitrary anyway. The only issue is that American states cannot pick DST without a federal law change.
> As someone else pointed everyone is already on DST for approximately 65% of the year. This just removes the remaining 35%. Picking standard time would have been a much bigger change.
This 65% started during the Dubya presidency (source: I was there updating tzdata on systems), and previous to that it was a 50/50 split.
So 65/35 or 50/50 is arbitrary.
But the reasoning for that was a preference for DST.
Obviously all this is arbitrary including standard time.