That mindset is indicative of security theatre to me. But as security theatre is common in entrprise IT that does not surprise me.
Pretty much everything supports SAML. If you decide not to support one of the standard protocols for SSO, you'll lose out on customers. Your tool has to bring in a lot of benefit (and have no competition) to warrant upending a company's entire auth system for.
Makes sense for GP locally, I guess, but globally we’re all worse off when nobody is motivated to break free from the path of least resistance.