Features and missing features

[xoft]

It's not about replication, it's about keeping things in sync. When you shoot an arrow, you want it to go in an arc with the expected speed. If the server ticked a few chunks on the path in a different thread, the arrow will glitch forward and backward on the path. Similar with all entities crossing chunk boundaries. And the code will be a terrible mess, very difficult to maintain. Redstone would definitely not work properly - on a chunk border, the order of evaluation would depend on which chunk would get processed first so the outcome will be unpredictable - which is something you don't want in redstone.