An example of it being done right recently is Lies of P. The level design does an absolutely fantastic job of drawing the player's attention to areas of interest without being needlessly obvious or gaudy. For example, ladders all have a grate at the top of bottom the sort of which you'd use to scrape mud off your boots before climbing a ladder. The presence of that grate is used in much the same way as the yellow paint that started this discussion while blending seamlessly with the environment .

Graphics improved, processing power improved, and along with it came a lot of visual clutter meant to make the gamespace feel more lived in/real. This works, but also makes it harder to pick out things that stand out as abnormal.

In older games*, gamespaces were a lot more simplified and minimalist, so anything vaguely out of place immediately pings as "interesting" and should be investigated.

*Mostly, old adventure games and their "pixel hunts" had this exact issue as well.