This is basically how land worked in Second Life. LindenLab charged a set price for a parcel (by size) or island (by compute), regardless of what was on it. They didn't calculate that by continually assessing the earnings of the land (which seems awfully close to charging for the improvements and not the land itself, and a staffing issue). The prices of islands changed over time, though I don't think parcel charges increased (haven't paid attention since I stopped working there).
Land owners had to pay the above price to LL monthly. They could then resell/rent to other residents.
I think your positioning is wrong. The problem this solves is auditing user accounts in SaaS applications. That is a great problem to be solving, and you can position yourself on that! Why talk about 'SSO Tax' when this has nothing to do with SSO?
However, I like how you're scraping web data for apps that don't have APIs. I've been waiting for someone to do that. That said, I want it built into other tooling I have purchased, so I don't have to implement myself.
Land owners had to pay the above price to LL monthly. They could then resell/rent to other residents.