Why do I need to create a sub-account to add more websites?
The number of websites that can be created under an individual account is limited, however the number of sub-accounts is not limited. Meaning as long as you keep adding sub-accounts the number of websites is effectively unlimited.
These restrictions are in place to reduce your (and potentially your clients) exposure to hackers. Each account has access to all of the websites beneath it, meaning if one site is compromised potentially all sites are compromised.
Creating multiple accounts results in multiple, isolated, spaces for websites. In fact our advice, as a step towards optimal security, is to create a unique sub-account for each website you host.