Why ? For performance reasons. I know there is other old suggestions about it, but I think it really need attention now.
By My experience playing online, I have a felling that its not the current combat mechanic ( damage done by blocks insted hp ), or the number of players, that lags the servers, its the size of the ships.
If there is 200 players in the same server with small ships, it will be easier to the server to handle it then 2 players with 3m blocks ships each.
Any ships with more then 3m will lag alone all the cluster, in battle, two of this will crash any server.
In fact, almost all servers have limits for the number of blocks for ships to 1m, but since its not blocked by the game and its hard to control, there is always someone with a big ship or building it.
It could be disabled by server configuration for those who want to play lagging servers ( but not recommended ).
Its easy to do on the game code and would fix a lot of issues.
Also, it would make easy to make balance between the ship x sizes, since you know the max size of an ship, you can guess the firepower of it.
And it could encourage artists to build smaller ships, for this, some blocks could have a lesser count, like, 2xdecorations blocks count for 1 on the ship size or even 0.
