Some type of "enemy danger indicator" is a must, especially for people not familiar with d&d and typical monster difficulties. I agree that this doesn't necessarily have to be a level indicator. But I worry your suggestion could be difficult to implement...could you tell the difference between a level 7 vs 17 fighter from a cutscene?
I strongly disagree. Let the context suggest which characters should be a poor idea to cross. And let the player pay the price if he goes out of his way to ignore the warning signs.
It worked flawlessly for years. Not sure why D/D would now suddenly need to flag enemies by levels.
100%
Yo that quote is like 4 pages old. Since then I've become more convinced that an "enemy danger indicator" isn't necessary (on low difficulties it probably should be there: why not?)
BUT. A level indicator
is necessary if there are no graphical differences between a "level 4" red dragon and a "level 15" red dragon. If, as I said in more recent posts, stronger red dragons look different and/or have different names, then that's enough of a signal to the player.
Again, D&D works because the stats of monsters don't change between encounters, and if they do, the DM tells you "this monster looks stronger, meaner, etc"