The limit is actually on the sending of information.  Also, energy has
mass so tends to be restricted by the same rules as conventional matter,
with the exception that, in certain cases, the mass is finite at c.
True FTL communication would cause causaility problems as, to some
observers, reception would precede transmission.

In theory... since we have never actually transmitted communication
faster than light speed.

I think we could easily avoid casuality issues by simply using built in
delays with timestamps that would allow transmissions to be received in
a simultaneous manner that would not violate natural laws.