There's a whole monster first design part to that article. It's indexed to create monsters to fit certain tiers, but that's fine. Monster first doesn't mean I'm not paying any attention to where I want to use it. Personally, I don't design new monsters in a vacuum. I don't design them with a specific encounter in mind either, but I am usually designing for the campaign I'm writing, and that campaign usually has a level range, as does the specific part of the adventure I'm working on. Using the design principles in the article you build a monster and it'll tell you what portion of your budget it'll take up (to borrow a phrase from your post). That could be the whole budget for lower level characters, or just a part of the budget for higher level characters.
I'm not saying it doesn't
work. 4e proved it works. Building encounters was a breeze.
But it has some flaws. You can see it in the design table; the mob (11-20) monster at adventurer tier
doesn't correspond to any monster on a previous tier.
Monster-first design means that CR 1/2 orc is (in the above system) worth 4 EBP. 12 of them are a (EBP 48) hard hero-tier encounter, 18 are OMG difficulty.
In encounter-first design, you want a hard encounter with 12 monsters, which in turn determines the stats of said monsters.
You can still say "I want a hard encounter of orcs. How many orcs do I need" in monster-first design. Just like you can whip up orcs, and say "ok, what would 12 of these be appropriate to face?"
But the focus and what is easiest is different in the two cases.
You can make a hybrid system, where you take the encounter-first tables, build monsters that are multi-role and capable of serving more than one purpose. This is quite viable, as well (basically, because both encounter and monster first work, half way point works too).
The 5e design focus was intentionally monster-based. And by going back to encounter-based, you gain some (real, solid) advantages, but you also lose stuff as well.
For an example of monster-first design pain and pleasure: A medium sized 5e monster with a short sword deals 1d6+stat bonus damage per swing. If you need it do deal more, you need an
excuse. If you know you want it to be X tough, you know that isn't enough. But you don't
start with "it deals 10d6 damage, because it has a damage budget of 35". You start with 1d6+3.
Now your job is to find a way to justify it dealing about 35 damage per round, given that its sword deals 1d6+3 (6) and it is medium sized. Well, it could have 5 and a half attacks per round; that might fit the concept. But it also might not. Maybe you can boost its stat to 20 and give it a "fighting style" that deals an extra 1d6 damage, so now it deals 2d6+5 (12) per swing. It swings 2x per round, and 3x per round once bloodied (below half HP).
What was that fighting style? Does it have any other impact, other than just boring raw damage? That kind of embellishment can enrich the monster.
Plus, now that it has some kind of elite fighting style, are there any clues that it has that style? Is there an organization? Is it in common with other creatures of that type?
This is all
work. And it is much, much easier to just say "1d6x10 damage with its sword". Which is part of why 4e worked. But there is ROI when the monster is simulated and then judged (and then maybe cycled back and the simulation modified to suit a role).
