So here is a prime example off you letting us know you're an armchair dev who show you have no idea what you're talking about. First of all, google and blizzard doesn't exactly do the same things. But lets pretend they did.
Your version off more "servers" would end up in more realms. Which they are doing but they and we all know its a bad solution, long term.
They can't just add more servers to keep expanding the megaservers, that technology does not exist. They have reached that cap.
Here is another fitting quote, to show you really don't know what you're talking about
Do you really think it's that simple? Just a login? That the entire thing that happens? You also log straight into the server itself dont you?
A blue post about the same topic.
"Realm capacity is dictated by the total number of connections that the service itself can handle. Every time a player connects to a realm, that connection interacts with numerous services, systems, and adds to the total load on the persistent database that the entire game relies upon to fetch data related to players, spells, quests, creatures, Auctions, etc. When that total number of connections to a realm’s DB and services reaches a certain number, the service will degrade or fail on multiple levels, leading to symptoms like severe Auction House lag or outages, Chat performance degradation, or lag when attempting to loot items. Never in wow’s history had the capacity of realms been as high as they are now, and even with our modern capacity we can still sometimes experience performance degradation when the realms are full and DB load is at its peak."
But sure, you keep believing you know better AND that blizzard should call you for free help in solving this issue... please...