Is there a link between the market for security engineering talent and the leverage that the security engineers have within their organizations? Are you seeing anecdotes play out in the industry that inspire hope that the balance of power in business decisions is shifting toward the engineers?
A literally equivalent way to look at the SSO tax is "the no SSO rebate". As a security engineer, I'm not prepared to launch a moral crusade over SMBs who don't adopt SSO on all their random SAAS apps; meanwhile, we're SSO on everything, and it costs us extra money, and that's life in the National Foosball League.
If it's actually true that we have crossed the point where it is no longer prudent for companies to segment their customers this way, then there are a whole lot of companies making unsound business decisions, and the problem will solve itself.