It doens't matter if it's Guild Wars, Dark Age of Camelot, Warhammer Online, all of these games have had to face the issue of servers lagging out when hundreds of people rush towards a battle zone. The zone population goes up, the server requests increase and eventually lag commences. To solve this issue lots of things have happened over the years.

We've had advances in server technology and load balancing techniques. Allowing servers to handoff zones to more powerful clusters. Some games simply choose to instance a zone and throw a hard cap on a zone. Some games like EVE change the time mechanics themselves to reduce the load on the server.

I'm wondering could this type of solution fit in a RPG. Would decreased movement rates, increased refratory periods for skills decrease the server load and allow more players in a zone. Would this kind of more strategic combat be acceptable to gamers?

If they could throw an extra hundred players into a massive battle would it be worth this kind of effort?