I think the difference between not listening to me or you telling them to follow the rules is along the lines of “what the hell do you know, and my dog isn’t doing any harm anyway (or so I’d like to believe), so I’ll do whatever I want”, whereas at least one sign in an area with an actual, informative accounting of the potential damage is educational and serves to bolster both the efforts of actual bylaw officers or wardens and of concerned nonofficials.
I think the same applies to other types of environmental law-breaking that are becoming more and more prevalent in parks, e.g. tearing up natural outcrops to stack rocks (but it’s oh-so “spiritual” to do so!) and build useless cairns and fake inukshuks everywhere. It used to be that material that explained both the points of interest and the rules was given out at national park entrances… but that’s a thing of the past in this area. With not enough wardens/bylaw officers to make a meaningful difference, this information about why these laws exist and what they intend to protect still needs to be disseminated somehow. An explanatory sign with meaningful information positioned at a trailhead would be one way.
Such information changes the narrative from one of “you people (that want to restrict my ability to let my dog be present or to run wild) just hate dogs!” or “you just don’t want anyone to have any fun (by tearing up outcrops)!”, to a defensible statement about conservation.