But why? Unlike with a public company, startups have needs from their investors beyond just cash. VC firms aren't just wallets, they provide services, access, networking, support etc.
This would skyrockets the small investments on early stage projects -> more projects would grow -> they go to VCs when ready
Why would a startup want just anyone as an investor?
You have a two sided market. It needs to attract both investors and startups to be a legitimate vehicle.