Epic pulled it off. Hell, they have crossplay from iPhones to PC. What did they do different?
What did they do differently? The made the most popular game of the last 5 years, if not of all history: Fortnite. A game so popular that many people declare it to be a cultural phenomenon and who has an estimate of more than 125 millions of players. To put that in perspective, after 5 years we, the Elite players, have not mapped that many star systems and we have people exploring 24/7 and going out in massive explorations that last months with about 10,000 players.
The result is that it is estimated that in 2018 Epic made about 2.4 billion USD in revenue in 2018 from Fortnie alone. Again, to put it on perspective, FD made £34.2 million in revenue in 2018 according to their financial report from
all their games.
Epic is several orders of magnitude ahead of Frontier in bargain power. There can't be a comparison between a company that organizes a Game World Cup of their prime product giving awards of $30 million USD to the winners, and a company that makes somewhat more than that prize money in total revenues.
Thus, I have no evidence but due to that success, I suspect that Epic didn't ask MS, Sony, Nintendo, iOS and Android to make cross-platform possible, but actually they begged them to enable it on their platforms.
The fact that we can share the same BGS without having different servers for each platform is quite a feat in my opinion.