So, most except for 6-7 viable decks? hmmm.
Yes actually. The original "official" archetypes were 2 for each faction with about 1 - 2 more added during the open beta period and Midwinter.
NG: Soldiers, Spies, Reveal, Alchemy
SK: Self Damage ( GS), Damage ( Axemen), Cursed, Discard (Tuirseach got expanded upon during Midwinter)
ST: Swap, Handbuff, Spells, Movement (Originally, Elves and Dwarves during the closed beta, Elves focusing more on ambush and Vrihedd Neophytes, Dwarves more on resilience)
NR: Machines, Swarm (Blue Stripes), Armor, Cursed
MO: Hazards, Consume, Moonlight, Deathwish
In the case of SK, the damage archetype was originally one, but split into self damage and damage later on. You probably remember.
For NG, Spies and Reveal, so fully half of them, aren't viable. For NR, Cursed and Machines (talking about archetypes. I'll get to hybrid decks later on) are also not really viable anymore. Nor is armor as a full archetype. For Monsters, we've got Hazards (Eredin Frost, Dagon Fog) and Moonlight, which are both not viable. Deathwish barely performs in the very high ranks, because of GS which counter it hard.
ST has Swap which works, but nothing else is as good.
In terms of official archetypes, SK has it better than pretty much most factions, as Veterans could be considered an official archetype after Midwinter, so they get 3 very viable archetypes and one which has certain variants that work (Cursed)
What's the point? viable decks exist all over. Viable official archetypes, not so many. Most of the decks we see are Hybrids. Even the Deathwish variant is a hybrid of Deathwish and hazards. Foltest in particular is often a hybrid, sometimes focusing more on armor, sometimes on Blue stripes and often packing some machines.
And here's what I mean by deckbuilding with NG being hard. Their cards, most or all of them, belong to official archetypes and won't work outside those. Unlike the other factions, in which you can make excellent hybrid decks (Foltest - Redrame's Redanians), In NG, your deck will be any of these 4, or Mill, usually, rarely diverting, even a little, from its targeted goal. While there are cards in NG's pool which have a more general purpose, most, by an extreme, amount, are designed with their parent archetype in mind. You can't really make a hybrid deck, at least not as easily as you can with factions such as SK, MO, NR, or ST. Coincidentally every other faction out there.
Also, saying that Alchemy and Soldiers are not particularly easy to play is disingenuous. These are prob the next easiest decks to play after Veterans.
They aren't necessarily hard. But they aren't easy. In my opinion always. I've tried alchemy a LOT. It took ages to learn how to play and build my own functional alchemy deck. Reveal and Spies are a lot more difficult to play than Alchemy. Especially the latter, notoriously so, but even the former requires tight navigation to make sure you aren't stuck in a short round 3. Greatswords, Vets, Deathwish, Swap, Frost, NR Hybrids, not necessarily harder to come up with in the first place, but definitely easier to pilot IMO. Alchemy ranks in between, as harder than the aforementioned but easier than Spies, Reveal, Axemen, NR Cursed (and now, with the patch changes, Machines), etc.
Of course that's just my opinion. Certain decks require certain mindsets. Maybe it just took me this long to "tune" into Alchemy's mindset alright. But that has been my experience overall. Adjusting and learning to play alchemy efficiently took me longer than pretty much every other deck in the game except Spies, Nekkers and Axemen