Comment by ndsipa_pomu

The concept of land ownership is somewhat flawed (how can you "own" something that existed before you and will outlast you) and there's a finite amount of land available for various purposes, so for the benefit of humanity/civilisation it can make sense to ensure that land with certain properties is kept for the purpose of growing food or for hosting particular ecosystems (e.g. rivers).

Even if it's not agricultural land, there can be strategically important pieces of land that a country will insist cannot be sold to organisations that are opposed to the values of that country. However, in those cases, it might make more sense for the state to make compulsory purchases of that land.