Every job application process has its own kinds of luck and failure modes. The time scales of academia lead to very different distortions than those in software engineering.
I don't understand your rhetorical questions. Clearly, yes, conferences choose bad speakers sometimes.
I readily agree these selection processes are not perfect, and institutional nepotism in particular is an issue in academia.
You can get a coding job just by acing a coding interview (and having basic social/professional skills). So this part of your comment did appear to suggest that merely publishing papers can be sufficient to obtain an academic position.
What possible reason would I have to interview someone if they had neither relevant experience, nor a degree? Should I just ask random people I see on the street to come in for an interview?
If you're talking about people who have no experience in the sense that they've never written a line of code, then no, obviously not. But professional experience and relevant qualifications are not necessary.
As with any job application, you need to have something going for you. It just doesn't have to be any of those two things.
Prestigious invited talks don't come out of the blue, but usually as a result of consistent work that people care about.
If a researcher can't get their papers published, in an activity where that is a key metric of success and the key communication medium, what's the basis of the 'really good' assessment?
Look at the list of keynote speakers at any major conference you understand. Are those the wrong speakers? Did they get this privilege unfairly?