You can do that at level 8 by rewriting the monsters.
As I posted,
Advancement in D&D has a significant arithmetic component. It's always possible to compress or expand the arithmetic of levelling into fewer, or a greater number of, chunks ("levels").
So I'm not sure what point you're intending to make, that you think I'm missing.
1E did it. The demons etc were weak sauce by modern standards.
I'm not sure what "it" means here.
But anyway, an AD&D Type VI demon has AC -2, which is the same as a fighter with Plate +1, a shield +2, and DEX 15. It has an average of 44 hp, which is in the same ballpark as a 6th level fighter with CON 16 (average 45). Its THACO is 12, the same as a 6th level fighter with +3 to hit and using the optional rule for fighter attack progression. It does 2d6 damage on a hit, or possibly more, with its whip and flames - but even the largest one does only 4d6 (average 14) damage with its whip and flames. A fighter with a longsword +2 and +3 from STR is averaging 9.5/11.5 (vs S-M or L) per hit; and at 7th level has 3/2 attacks, which gives damage in the same ballpark as the largest Type VI demon.
So in melee, an AD&D Type VI demon is in the same ballpark as a reasonably equipped 6th or 7th level fighter. It's ability to Cause Fear at will, use Suggestion at will and draw Symbols are a good chunk of the threat that it poses.
A 6th or 7th level fighter in AD&D is clearly not a demigod or even in that ballpark. The MM tells us that a bandit gang is led by a fighter of 8th or higher level. So the natural conclusion is that, in AD&D, a Type VI demon is about as tough as bandit chieftain.
Whereas in 4e D&D, a Balor (Type VI demon) is a 27th level elite. This is in a completely different category from a bandit chieftain: in 4e terms, a bandit chieftain is a Heroic tier, or perhaps a lower Paragon tier, opponent.
Have a look at the lvl 29 powers in 4E. Compare to synaptic static in 5E.
Here is Synaptic Static:
5th-level enchantment
Casting Time: 1 action
Range: 120 feet
Components: V, S
Duration: Instantaneous
You choose a point within range and cause psychic energy to explode there. Each creature in a 20-foot-radius sphere centered on that point must make an Intelligence saving throw. A creature with an Intelligence score of 2 or lower can’t be affected by this spell. A target takes 8d6 psychic damage on a failed save, or half as much damage on a successful one.
After a failed save, a target has muddled thoughts for 1 minute. During that time, it rolls a d6 and subtracts the number rolled from all its attack rolls and ability checks, as well as its Constitution saving throws to maintain concentration. The target can make an Intelligence saving throw at the end of each of its turns, ending the effect on itself on a success.
That's fireball-esque damage, combined with a modest debuff.
Here's Word of the Gods, a 29th level Invoker power:
Daily * Charm, Divine, Implement, Psychic
Standard Action, Close blast 5
Target: each enemy in blast
Attack: Wisdom vs Will
Hit: the target is dominated (save ends), Aftereffect 3d6 + WIS psychic damage
Miss: 6d6 + WIS psychic damage
I don't think Word of the Gods is much like Synaptic Static, either in its fiction or in its play.
Here's a 15the level Wizard spell:
Charm of the Dark Dream
Daily * Arcane, Charm, Enchantment, Implement, Psychic
Standard Action Ranged 5
Target: one creature
Attack: Intelligence vs Will
Hit: 2d6 + INT psychic damage, and the target is dominated (save ends). Until the domination ends, you are removed from play. You can end the domination at the start of your turn. When you return to play, you appear in an unoccupied space within 5 squares of the target.
Miss: Half damage, and you are removed from play until the start of your next turn. When you return to play, you appear in an unoccupied space within 5 squares of the target.
That's a pretty interesting possession ability. For plainer domination, the Psion has a 15th level daily (Domination) and the Invoker has a 19th level daily (Forced Submission).
4E youre pretending to play high level. You're really play level 9/10 maybe 11 max on a stretched out treadmill.
They lowered the power level to achieve it
I haven't read a huge number of accounts of 9th to 11th level 5e play. But based on what I have read, plus the rules, I don't see that much resemblance to higher level 4e play as I experienced it.