It’s because of (1) built-in factoring and infrastructure, (2) built-in domain expertise that would otherwise require hiring or training, and (3) contractual guarantees that can be invoked when things go wrong. All of which attenuate risk and make development timelines and outcomes more predictable.

Yes, I believe I also said that in some other point. I've been there and totally agree with him.

most businesses aren’t old enough to handle the responsibility, and that’s why we still sometimes use shitty proprietary software.

Once they become "old enough" nobody wants to personally be responsible for anything and politics and corruption get involved and you keep buying proprietary shit.