I am not quite certain of that myself. When doing some show and tell in a thread over a year ago now, I asked a former member Shadoza if he had this abilty, and if memory serves me correctly he had some, but not all of these freedoms. The threads showing some of the places I could build are posted below. Unfortunately I cannot check the details of this conversation within, as he has closed his forum account, and they are no longer present. But even then, this was a much older version of the game.
Pure speculation here, but perhaps it has something to do with the PC version not having a ‘true’ offline mode. 
By this I mean that it is possible to play Singleplayer mode, but the PC must still be hooked up to the internet, juxtaposed to consoles where we do not require a connection to play at all. Case in point, I have gone quite literally months at a time without even hooking my ps4, and for that matter Conan Exiles, up to the internet. Or perhaps it was just the best bug in the history of the game. 
I cant say that I have seen this option on my console before. Is this in the base game or is it a feature added by a mod?
Honestly, that would be more than enough to suit me. It would mean two things for me at the end of the day: I) that we can still place community Maprooms near Obelisks, and retain the creative freedoms that this phenomenon offered, including being able to build in the Unnamed City. And II) the most important for me, that we can still place a Bedroll in a dungeon. Intended or not, this was for me the single biggest Quality of Life feature in the history of the game. No Im serious! Its not that the others were unhelpful, but the convenience thos offered Singleplayers and Admins cannot be overstated. I would need a separate small post to do it justice as to why, so if you would like to know then ask me to elaborate hereafter.
Perhaps, but I would still prefer to wait for the proverbial word from upstairs. It may be, but it seems more complicated. For example, the fact that the pieces on the are no longer showing as owned, yet the ones in the center are. Unless the restriction functions as a virus of sorts, sending false or conflicting messages to all items attached to it. And if so, it only affect building pieces and not placeables. I know it comes off as a kind of silly analogy, but I am struggling to understand why it is just so erratic and inconsistent. 