I don't know when the fuck developers lost the art of making shit easy to pick out, but the best example of putting focus on stuff without making it horribly obnoxious is Resident Evil 5.
Players have a subtle black outline on the along with being way fucking brighter than the surrounding area, making it really easy to pick out your partner from other people, especially considering that the main characters use comparatively more vibrant colors than the zombies where they're all more muted greens and reds.
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(Red box just to point out the outline since it's really prominent on her legs probably due to the skin mod I have for Sheva.)
Boxes will often be more lit up than the surrounding area, making it obvious that they're a breakable prop. It also adds that your AI partner will walk up to boxes and break them, telling you that you can do the same. All of this shit is an easy pointer without making the game unbearable to look at like they later did with Resident Evil 7 + 8 and the remakes.
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I agree with pretty much everyone that this is partially the result of the pursuit of hyper realism and lack of style in videogames, but also like everyone points out, there's just some straight up retards out there that don't know shit. Even people who basically play videogames for a living can be absolute downies when it comes to figuring shit out. One of my favorite examples of this was the YouTuber M3RKMUS1C playing Titanfall 2 and got to the time travel mission on his Nerd Plays channel. He fucking struggles to comprehend the most basic of "puzzles" in an FPS game.
https://youtube.com/watch?v=J_TvnuoFOzc