In the time of broadband, "server load would make it unpossible" seems like a pretty silly defense, but it's possible that it isn't.

At 256 Bytes per message (~200 potential characters + transfer information), sending that information to 4000 players would result in less than 1 MB of traffic for SE (~.25KB for players). Still, 1 MB * 3 shouts per minute = ~4 GB more bandwidth per day = ~120 GB more bandwidth per month

Realistically, this probably works out to about ~$100/month more in costs per server, so Profits -$1600/month. No one is going to unsubscribe if this feature isn't implemented or resubscribe if it is, so they have no reason to cut their profits.