I agree, but only in a consumer environment, such as games and other trivial consumer apps with a lot of free sign-ups, when storing none or very little PII, wh

I agree, but only in a consumer environment, such as games and other trivial consumer apps with a lot of free sign-ups, when storing none or very little PII, where SSO/etc aren't ever going to be required. These SaaS products are far too expensive for free consumer apps. Otherwise, if you are going to be selling into the enterprise and the majority of your users are paid, this is an area where using a SaaS tool is a no-brainer. Your sales team is going to run into customers that need XYZ-compliant auth and it's solved out of the box with the SaaS and cost isn't an issue since it'll just be baked into the per-user pricing.