Maybe I'm just wired differently in the brain to others, but it seems to me that this and the 4e "monster design matrix" are just different sides of the same coin. The only difference is that, when I'm designing monsters (or, more usually, modifying them) for an adventure the 4e way around is slightly more useful. Could I generate the monster descriptions, assess a rough AC, hp, Dmg and so on from that and then convert that to a level? Sure; but then I could end up futzing around designing several creatures until I got one of the level I'm looking for to fit the adventure and party level. Alternatively, I can set an AC based on the level of monster I want and then ask myself "what armour does that mean it has?"
The basics are sound, as long as "monster level" is there to give an accurate idea of how dangerous this monster is, though. The answer to "what happens if this (level 1) goblin gets maille armour and a greatsword?" is "it becomes a level 3 goblin".
Yeah, this is how I build monsters in 4e.
But I go a step further:
I also look up, what Weapons and which PC class could resemble my NPC.
So I say: I want a level 3 lurker:
An assassin, executioner.
17 AC: dex 18 + Leather armor + 1/2 level MAke it 20 dex and don´t have him wear armor and a secondary weapon instead. (he can later be encountered with armor and is a bit more beefier than)
Attack bonus of 8: longsword + dex bonus. Check!
Damage: 1d8+1d8+5. maybe a bit too high. 2 daggers instead. Reasonable. (Longsword for the times when he wears the leather armor)
Lurkerness:
assassins strike +2d10
death attack (unconscious attack against PCs)
sneak attack 1/encounter? why not.
and a rechargeable hide in shadows ability. And the ability to hide with partial cover.
5 mins, moster done. This is what works great in 4e. If you take the time to make up some reasonable dressing. However HP and such is rather inflexible.
You can play around with brute and soldier and artillery... but it makes the system rather inflexible.
If you would reverse the process, you would have:
Assassin PC class level 3.
longsword and leather and 2 weapons. Great AC and high damage. And abilities to attack from surprise! HP are not that high.
-> Makes him a Lurker. Challenge level 4, if he can play to his advantage. Otherwise only 3. If the players catch him off guard they still get full xp.
So maybe a PC class in general is about one CR higher than a normal monster in 4e. Defining challenge rating right in 5e, (measuring in PC class level, a monster with a PC class minus some fiddly bits) is CR equal to PC level, and in a 1 on 1 fight the PC, because of those fiddly bits like Theme feats or magic items will let the PC win most of the time, but usually only barely.