Go load www.amazon.com and check the source right after </html> :)
Another anecdote: somewhere in that time period we (Prime) were using comments for various metadata and pre-release and post-deployment checks would verify the comments were in place. The team responsible for the edge proxies decided they were going to rewrite all the HTML going out on the fly to remove extraneous comments and whitespace in an effort to reduce page-size.
In the middle of testing a release all of the tests related to a particular feature started failing and (I believe) different devs were getting different HTML on their systems (the feature wasn't rolled out to every session). Our QA team was extremely pedantic in the best way possible and wouldn't allow the release to continue until testing could complete, so we had to track down the responsible parties and get them to dial down their transformation. They eventually tried again without stripping comments, but I can't imagine much was saved after compression without much of anything removed (they might have been rewriting other tags as well).