This is just asking for a long off-topic thread but as one of HN's resident SSO nerds: you don't have to listen to people demanding that you eliminate the "SSO tax". Paying for SSO is super annoying, and I'd rather not pay it either, but I'd even less rather see companies go out of business because they're not generating revenue. This "tax" is popular because it's one of the more effective customer segmentation levers that exists.
Since this is (apparently) one of a zillion companies to do this, I think we should probably just treat this as off-topic and make our great stand on Rob's sso.tax page somewhere else.
Custom negotiated contracts (including NDAs), custom billing terms (although this is harder to segment on), advanced team management features that allow separate parts of an organization to use your tool (think sub-team management w/ individual admins and configurable visibility between teams).
Since this is (apparently) one of a zillion companies to do this, I think we should probably just treat this as off-topic and make our great stand on Rob's sso.tax page somewhere else.