Old splinter cell and other stealth games still used on screen indicators of stealth. It was never "simple lighting" that made the player understand if they are "in stealth or not". It has always been up to the game designers to make visual understanding of what is hidden and what isn't hidden, this has nothing to do with graphics.
Yeah, those stealth games never really clicked for me, with their absurdly imperceptive professional guards standing around everywhere.
Two examples that immediately come to mind are trying to fight in World of Warcraft when underwater (where I had no eff'ing clue where exactly the enemy actually was, relative to my character) and overly flashy effects in games, often MOBAs (where they were taken so overboard to where I had no idea what was even happening on the screen).
I'm surprised people put up with either of these. I found both of them in and of themselves really frustrating and detracting from the fun of just playing the game.
I'll give an affectionate shoutout to Transistor; one of the mechanics is having to deal with paparazzi-like monsters that are just flying cameras whose difficulty is in obscuring your screen with flattering action shots of the protagonist. Lazy, but clever and adorable!
The core issue, however, is that what the player sees on screen must align with the UI. Baked lighting created hard, discrete boundaries, but modern ray tracing outputs a continuous gradient of scattered light. This inherently creates systemic confusion between the visual feedback and the UI.
The only workaround is to design areas of absolute, pitch-black darkness. But doing so severely restricts level design, not to mention that 'realistic' absolute darkness practically doesn't exist in the real world anyway.
I find myself agreeing much more with the game designer's perspective on this one