Strong disagree. In my experience, this is not commonly why competitors don't adopt Google's practices. The main reasons I've seen are:
1. Money. Google essentially has a giant, gargantuan, enormous, bottomless pit of money to build a lot of this tooling (and also to take the risk if something ends up not working out). I think you might be able to say that other companies are just being short sighted if they don't implement some of these things up front, and that may be true, but (a) that's pretty much human nature, and (b) given that very few other companies have a bottomless pit of money like Google, that may just end up being the right decision (i.e. survive now and deal with the pain later).
2. Talent. This is closely related to #1, but few other companies have the engineering talent that Google does. If there is one thing I've seen with my experience with ex-Googlers is that most of them are fast coders. So when you go to your boss and say "I'd like to implement engineering/tech-debt improvement XYZ", at other companies it's a harder decision if (on average) it would take 9 months to implement vs. 2 or 3.
3. Related to both of the above, but your 4th bullet point, "Quiet accretion, over several years, of the [[whatever]] by people who understand it.", is actually other companies just waiting for more evidence to see what "shakes out" as the industry-standard, optimal way to do things.
4. Finally, your stage 1, "We're not Google, we don't need [[whatever]]" is actually true in tons of cases. Many of Google's processes are there to handle enormous scale, both in terms of their application/data capacity, as well as the sheer number of engineers they need to coordinate. Very, very, very few companies will ever hit Google's scale.