> And yet there has been no operational impact at Google since the layoffs...so maybe they weren't so critical after all?

How do you even know that?

Usually the only way that you will see that, as a customer, is when the people who left are unable to keep up with all the firefighting and things ultimately explode. Either with outages or a security breach.

You can accumulate a _lot_ of tech debt before customers notice. For smaller companies, that's often a fatal amount of debt.