Because it's not their company mission to provide an HR tool. Getting started fast doesn't equate to being done somehow; every piece of software still is a liability that requires ongoing maintenance and continued development.

I don't believe everyone will just suddenly start to replace SaaS tools with agent-built versions of them, because economically, that doesn't make sense: Even when we gloss over all human work still required in collaboration with agents, the tokens alone required to build a sufficiently complex system are more expensive over the long term than buying SaaS seats. So there's that.