Carriers have the same laser weapons as stations.
They destroy your shield then shred your hull in a matter of seconds, I tested it by shooting my own carrier the day I bought it.
You do need to do quite a bit of "damage" for it to shoot back. As long as you don't have a valid bounty in the system, shooting your own carrier doesn't give you one, you'll respawn on your carrier.
They'll also use those same guns on any nearby mines, regardless of what may be in the line of fire.
Many search and rescue ships have fallen victim to my carrier's laser light show and their materials have been put to good use.
Does cargo? We could reverse hydrogen bomb them that way - just keep filling up their cargo holds with cheap junk they'd have to get rid of to go anywhere.
Cargo does add to the 25000 ton/unit limit, but only the carrier owner has access to cargo transfer.
Everyone else needs the carrier's owner to set a buy order on the commodity market for the specific commodities you might try to dump on them, of which the owner sets the price and maximum demand.