Actually, a lot of sites keep updated posts with new information, which is useful. Which I believe makes it harder for Google to figure out who is gaming SEO and who are providing actual value.
How so? Could they not ML-detect the main body/content of the post and do a simple diff to previous "crawls" of the same content? You would think this gets picked up and somehow "resolved" because it's essentially a duplicate post or entry in their crawled pages DB.
If there is just a change in date and no change in content it could. But if the content changed, Google may not directly be able to state if the content was useful or not.