"...but instead of giving a small amount of money for 6% they get 50% of the company for a bigger investment..."
I think one reason is that most seed investments don't need to be that large, and large investments can actually be detrimental to the progress of a startup.
It's a good point, what I mean is, the big company gets 50% not to provide more money now, but to play the role of the few first next rounds if the company will be worth it, but ensuring the founders less dilution.
