Because it's a new genre.
And in that genre, up until the last few months ago with Battlegrounds coming out, there wasn't anything that was any good, there were just a few mediocre sloppy games that played about the concept.
Even then, battlegrounds is far from a polished quality finished game. It's janky, buggy, rough around the edges and still being developed. It looks and feels like a low budget indy game. Don't get me wrong though, it's a blast, by far the best of the bunch, and deserves it's success.
But lets put a stop to the phoney disbelief as to why consoles don't have it. It's brand new and not even finished. It's blatantly obvious why consoles don't have it, hell, PC barely even has it yet, it's early access.
"why is this 1 in a 1000, fun, unique, but difficult to run and demanding early access game that's nowhere near finished only on one platform so far?" Answer - "have patience"