Google is putting a lot of marketing money on the topic, but from what I saw they are trying to alert that there is no one size fits all for this.
I think people should realize that when you go into the hiring market looking for SREs, you are about to pay more, not less, for a highly qualified software engineer who is also a systems expert. You want these people to not just operate product, but to be closely involved in architecture and development so the product turns out to be operable. Your SREs should be working in the product code on the bits that ordinary developers might overlook or not be qualified to write, because they lack expertise in system or distributed systems behavior.
What this article is calling "real world" is just an attempt to redefine the term.
Any org I go into that says 'we want an SRE because google has one' I can not help myself I blurt out 'you are not google. what works for them will not work for you, you need to find your own way of doing this that fits your org. Trying to mimic google without the understanding of why they way they are will damage your org'
That matches my experience at most companies, the SRE/DevOps is just the sucker who is on call.
That's exactly how it is implemented in my company. We are called SREs but everything is driven my management (and by that I mean a single VP who is omnipresent).
Adopting another company's practices is often lazy thinking. There are no silver bullets.