Why VPC with a "public subnet only and AWS Site-to-Site VPN access" cannot be configured?

Hello, Private subnet only with AWS Site-to-Site VPN is the case when you want to restrict the VPN network in the private, there is no Internet gateway enabled over the Internet. However, there is no limitation to public subnet only with AWS Site-to-Site VPN, you can configure it if you want. For details see below AWS Doc. https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Scenario4.html