I genuinely disagree, even if it isn't where I normally sit.
The rules should be defined, in the Byelaws, and enforced, with prosecutions if necessary (though the first line should be a simple "pack it in or move").
I also want to see some enforcement of the existing Byelaws surrounding noise, and some modifications to them, applying to all trains and stations at all times. At present playing a musical instrument or device out loud is an offence only if it causes annoyance, which means it is necessary to complain for enforcement, which can be awkward. I would like to see this change to an absolute prohibition, and enforced without being asked, as it is simply rude. Headphones are cheap and easily available. It is not ever acceptable in any setting, other than a private home, car, hotel room etc or an organised event, to play films etc out loud, yet antisocial people are doing it with increasing regularity. This is adding to the increasing noise pollution of modern life, and it is totally unnecessary.
Though to be fair, waffling announcements are as bad, and are of no benefit whatsoever to anyone. Static information not related to the operation of the service should go on static printed posters, and the "don't leave your bags lying around" and "see it, say it, sorted" nonsense no longer announced.