Hate to break it to you but I'm playing since day 1 of CB and I've seen quite a few 1-2 deck dominated meta's. Besides pre-Swap patch, I don't recall any season with 4-5 GM capable decks. I'm talking about different types and different factions.
There is a difference between 1-2 decks being the strongest and 1-2 decks being able to compete at the top. Yes, playing something else is the harder road to travel. Impossible and more difficult are not the same thing.
I'd be careful citing GM as the barometer for "top of the ladder". In most seasons it has not exactly been what could be considered the very top. There the deck pool able to compete was even more expansive. There have not been many instances, if any, where a faction didn't have at least one option to get to GM.
This is a bit off-topic but: Are you aware that top was and is dominated by OP decks? Every damn season. Has nothing to do with the illusory "because they do not fully grasp how to stop, play around or deal with it" notion, which is a complete bs, if I may. OP decks are there for a reason. This comes from someone who usually gets to GM against the grain. Also, look up in the Pro-Ladder, most of the players reached their top MMR with SK already. "Coincidentally" SK is dominating regular Ladder as well. Why is that?
Here, we're on the same page. The top is often dominated by decks able to do overpowered stuff. This is why they're on top . However, in many of these cases you could conceivably run a build to counter the overpowered mechanics those decks were exploiting. The problem was it was either extremely difficult to do so effectively, doing so compromised your deck against other popular builds or some combination of both.
The inability to stop, play around or deal with it statement hinted at how the meta changes as rank changes. For most seasons there have been ranges where certain decks see more play than others. As you go up, the game play changes. Many players running to complain about a mechanic are going out, netdecking a popular deck, reading a 2-3 page guide and expecting success. They're not considering what they can change to counter the decks they're seeing. Incidentally, this is why the entire ladder gets swamped with OP builds after those top decks get... publicized.
P.S. At this moment, Gwent is a failure in my eyes. No uniqueness of factions, everything is pretty binary, apart from very few exceptions. Keeping it as it is, I'm talking about the current design, is probably a bad idea. It has to change and the changes need to be drastic. If Homecoming fails, I'd be bummed but at least CDPR tried. But this...
Again, right there with you. My personal issue with 3 rows is less about 3 rows itself. It's simply my opinion most of the times they have made a radical change the game has ended up worse off. Given this opinion, the number of times we have had huge, sweeping changes and the scope of the changes going into Homecoming I can't help but think it's happening again.