Very simple. A way to protect a large area at the spawn area so a spawn build with things like rules and server info can be safe from griefers / trolls w/o the use of unreliable command block setups that break / change how they function in every update.
This is something that has always been in java eddition since Multiplayer Alpha release in 2010. And now we are in a time that where a public open bedrock eddition realm / multiplayer world is a 100% must have to Live streamers and youtubers or you lose viewers / followers. Since 90% of anyone's Viewers are on a xbox / tablet or windows 10 sending people to a java server is out of the question.