That's your perspective, but let me try another one: So many SaaS products have a free/low-cost tier that allows people to get basic functionality for nothing or extremely cheaply. Users are clearly not unhappy with this and the vendor gets market share and awareness.
However, there is still a cost - and that cost ends up getting subsidised by commercial customers that have a hard need on a small number of features.
That, and the fact that even 'small' business customers these days make you fill out the same 'security review' forms that they don't understand and never read, can require a lot of hand-holding (especially if they have a procurement or legal person who wants to get their requirements in) and can take forever to do a Proof-of-Concept.
ALL of those things have costs and guess what, they end up being added to those small number of 'must have' features.
That is why a base tier might be free but suddenly you add something like SSO and the cost doubles...