I see it noted in the guidelines to players of multiple recently released OSR games (Dolmenwood, HMTW, others): "Avoid Unnecessary combat...players are advised to avoid direct confrontations where possible (DPG p. 143)"; "You should never expect the world around you to be fair...don't fight fair...don't be afraid to cut your loses and run away (HMTW, 16)." It shows up on OSR/NuSR focused blogs and forums all the time.
It's also evidenced from the fact that combat in TSR-era D&D is just so deadly. Yes, there are room-after-room of monsters who attack on sight...that doesn't mean you're expected to just go toe-to-toe or that combat isn't deadly or that you can't think your way out of fights instead of stand there hacking away.
I mean, look at the perennial favorite Keep on the Borderlands. Level 1 PCs against the Caves of Chaos. If you just charge in, you're going to die.
It's also built into the advice for referees, see the early modules and the AD&D DMG. Players were expected to play smart from the start and not rush into combat.
OTOH, there's a degree of expectation in D&D from at least 3.5 onward via the DM guidance & encounter builders & play culture that encounters are generally prepared to be something the PCs can win in a direct fight; and if there's loses you can probably recover them via Raise Dead, wands, whatever. Can you absolutely drift this away into whatever you want? Sure! OF course! But the system and ruleset is not set up from the basic point to do so in a way that has 0 expectation of "encounter balance."
Right. You can try to make 5E play like an old-school game but it's going to fight you just about every step of the way.
Some stuff you can easily do in 5E to make it harder or more like OSR games is the setting, crazy monsters, gonzo references, etc. But you're still going to have PCs with easy access to attack cantrips, darkvision, infinite bag space, long rests, lots of healing (even more with 5E Revised), overpowered spells, silly ritual spells like Tiny Hut, laughable exploration rules, etc.
Besides pulling out all the toys from the PCs, which the overwhelmingly vast majority of 5E players will not go for, you can drastically up the monsters. Start with double or triple deadly encounters in 5E or double to triple high-difficulty encounters in 5E Revised.