I think a better question to ask is not if it is relevant, but what portions of it are relevant. There are certainly many key, important lessons that have been learned in the process of scaling their organization and processes. I'd say it's near impossible that none of those lessons are relevant.

Copying their full process probably won't make you the next Google, but figuring out how to take their learnings and apply them at the right time is a great way to give yourself a leg up.

Consideration for applicability and scale is definitely a prerequisite for actually implementing anything but in my experience the biggest value isn’t being able to say “this is what Google does”. Anyone with any interest in opposing that sort of change has certainly mastered dismissing anything like this with “we’re not at Google’s scale”. The biggest benefit of all of their efforts in this area is that they’re leveling up the industry.

Collectively tech seems to evolve rapidly but at the individual/team/org level it’s rife with cargo-culture and resistance to change. It’s not even exclusively caused by stubborn behavior since change requires time and resources that may not be afforded to teams unless they can hitch it to a feature or initiative. When the big players level up industry practices they decrease the defensibility of sticking with old ways. New tools designed around the new principles and a million blog posts changes the landscape.

Show me any org or decent sized team and I’ll find you members of it that could have told you what needs to change in their environment to get to the next level but face an uphill battle. The big players not only give them supporting evidence with moves like this, they raise the bar or shift our entire thinking. Without that shift the holdouts can hide behind a lack of consensus and cargo culture.

That's why this book is called the Site Reliability Workbook. It is written to be appropriate for your company.