O/T: Closed offroad trails

I'm curious how many out there have run into their favorite trails closed to the public.

When I was growing up we had some awesome trails behind our house in Red Feather Lakes, Colorado- Part of Roosevelt Natl Forest.
There were cattle guards in place and where there weren't there were gates with Natl Forest signs asking offroaders to close the gates.

At some point, somebody bought the property in RFL that the access roads went through, fenced off the trails or put 3+ foot diameter boulders in the way. Access is impossible without causing damage to these fences (and visiting the big house if caught).

Confessing ignorance here, is this sealing entrance points legal? I really miss going back there- there were old miners cabins, streams, climbing hills, etc... Most people who went back there (myself included) never left the trails, never left trash, and in general we would tread lightly.
Such a shame.... Is this common these days?