Dibs implies a claim only

I am postulating that something more is required - to actually bring the land or resource under some form of productive control

The purpose of property is to prevent and resolve disputes. If I walk into your home and begin to eat food you worked to secure, you may object to my action. But if we know that the force of opinion of society is on your side even if you use force to expel me, probably I will not even try such a thing.

And for this to be a universal social norm which secures the poor in their small fortunes, it must also secure the rich in their large fortunes.

Moreover, the nature of property as a mechanism for resolving and preventing disputes requires that only certain methods of acquiring property are valid - appropriation from nature, or voluntary trade (including gifts and inheritance) with a valid property owner.

If property acquired by theft were legitimate, there would be no end to disputes, stealing and stealing-back.

This is precisely what makes the notion of property - even personal property such as the shirt on your back - completely incompatible with socialism, which is organized theft masquerading as the proper form of property.