This is a subject that really irks the engineering side of me. It's utterly ridiculous that engineering and efficiency decisions are so deeply affected by whether or not the largest search engine will properly index your content. Why is it that Google doesn't get flak for not discovering content that's engineered to send the absolute minimum over the wire, cache intelligently in localStorage and IndexedDB, and scale…
I would argue that it is nothing to do with Google.
Google's official line is that that will index your content, even if your entire frontend is a big client side only SPA. The explicitly tell you to focus on having good content that people actually want to read, and little else.
As others have suggested in this thread, it is likely that they developed Chrome for this reason. My understanding is that they basically crawl the web using a headless version of Chrome, and take a snapshot of the augmented HTML straight away, after 5 seconds, and after 10 seconds.
Other search engines aren't so clever, and so the work to have your important content available even when Javascript is disabled is done so you will show up on Bing, Baidu, Yahoo, etc also.
To go further, I reckon Google would love it if you didn't do this, as it would give them an edge over their competition which has less advanced capability to crawl the web.