Gmail's explosion of invites

I don't know exactly when this happened, but today I was checking my gmail and suddenly I have 50 invites left! And I do have two gmail accounts, meaning that I can invite up to 100 people! That pretty much means that there is only one thing that gmail does not allow: people have to have an email address to get a gmail address! This is the way you send invites, you give the email address of your friend and then this person receives in invitation. What is the reason behind Google forcing people to have another email address? Do they want to always keep track of who their competitors are based on where people send invites to? Or who they are smashing? With so many invites available, why don't they just open the floodgates? Afraid that people will have hundreds of gmail accounts to use as their backup system? Oh, well... Just thought I had to drop this note before going back to work on my dissertation here. It's getting there, but isn't quite there yet.