That particular dropped kerb was to access a property. It was not the type that is installed at the end of roads or particular points along long roads, with the specific purpose of helping those with buggies/wheelchairs etc cross roads.
I think there are accepted local norms for parking across your own drive, depending on traffic in the area and parking issues. In some areas such as those with terraces and limited parking, it is often acceptable to park across your own driveway. People use their 2nd car to block their first in. Neighbours expect this as otherwise that household takes up another pavement space by nit parking across their own driveway but elsewhere. In most areas, no-one will ticket people parked across driveways as a matter of course…just those reported as blocking the driveway of other people.
When there is no longer anything to access via the dripped kerv, as in the situation Op describes, Id park there if nowhere else. If view it as another roadside space like any other. I don’t think the roadside space ever belong to anyone. Leaving it clear related to allowing someone access to their property. But if it is no longer a property access, it no longer needs to be left clear.
We have several like this along the road where I live. Parking is fairly tight as some houses have drives but lots don’t. Anyone now parks across those no-longer used for access dripped kerbs. It might be the person who lives there or someone else. With one of them, the owner parks there most of the time and others choose to leave it free for them. Occasionally someone else parks there…no problem. The others are just used by locals who live there. The properties the access relates to also have another access and off-road parking and park there.
Honestly, who could complain about someone parking across a dropped kerb (not wheelchair access type) which does not give entry to anything? It is just part of the public road.