Some landowners I suspect hope that if they let the public footpath get poorly maintained and poorly marked, walkers will tell their friends its a bad walk, easy to get lost, and fewer will try to walk it. That if people can't identify the legal path across a field, they won't cross at all for fear of breaking the law.
Needless to say, this doesn't work well on the stubborn, hardy types who'll spend hours ascending hills for fun - but it might deter the more casual walkers.
Aye - this is definitely the case near me in North Wales - it’s normal to find posts that held trail markers hacked down, stiles festooned with barbed wire like it’s time for some trench warfare, and paths that just disappear into a bog, a river, or a newly built housing estate.
The local farmers generally detest ramblers, as it’s not unusual to find picnic leftovers, balloons, condoms, whatever, in a field with livestock, so I can understand their desire to discourage walkers. Heck, where I live most of the time in the wilds of Portugal, I initially had no reservations about people using our land to access the river - until they started leaving trash and faeces around the place. Now we have no trespassing signs, which saddens me, but I’ve picked up my last pile of shit and toilet paper.
Needless to say, this doesn't work well on the stubborn, hardy types who'll spend hours ascending hills for fun - but it might deter the more casual walkers.