Because it's a way to bridge different cultures and problems of each European area. Some startups can't move around, but would love to tap into what other startups are doing around Europe. The same is specially true for investors who normally only work locally. A structure where they can tap into startups all around Europe and chat with other investors, mentors, etc. is extremely valuable.

Plus, by operating in different countries we can leverage and scale certain things that help us help more startups. :)