Okay, perhaps "the fork couldn't go ahead without them" is technically wrong, but I feel the point stands overall.
I do see what you're getting at, but I doubt miners would jeapordise putting themselves in a situation where they find themselves in such stark contrast to the will of the users. But yes, regardless of how strongly they feel about new proposals, I suspect most users would still follow the path of least resistance, rather than risk being unable to transact by playing power games like that, which does bear out your point.
I think most USERS want only to be able to transact, and don't care much about the technology that allows them to. Whether that's LN, bigger blocks or whatever, and whether they have to connect to this or that node with their wallet doesn't really matter to most of them. By far MOST USERS DON'T RUN NODES. When I started out with bitcoin, I used a light wallet (electrum). I only started a full node much later, when I wanted to study the block chain with a hex editor. I couldn't care less about having a full node for my own few bitcoins that I bought to buy stuff on the internet. Later, I learned the privacy aspects of a full node, which is what interests me most.
Again, it would take a brave miner to willingly put themselves in a situation where they find themselves in stark contrast to the will of the users. It's simply not a profitable business model.
It would take a brave miner to willingly deviate from miner consensus, which is de facto the current protocol. Even though miners can signal without cost what are their preferences, truly hard forking AWAY from the existing consensus takes balls.
Plus non-mining full nodes are still deemed a valuable security measure in the unlikely event of miner collusion. Considering the current levels of what hopefully proves to be paranoia on that particular subject, it's not something we should take too lightly.
Well, if there is "miner collusion", a full node can inform you. But there's not much you can do about it (apart from maybe trying to cash out as quickly as possible, before the market fully realizes what happens... or doesn't care).
As I said before, miners are "locked in" to the current protocol, and it would take balls and foolishness to fork away on one's own. It is only when miners would be strongly convinced that they can fork away with a large majority, that they will tempt the adventure. In doing so, they will try to save their income as well as bitcoin itself. Most probably, it are the miners that would only dare to fork if they are mutually convinced of such a large majority between them that the old chain has little chance to survive. For that, they must be sure to be more than 80% or 90%. ETH/ETC showed that even 10% can survive. With bitcoin, it is true that the slow retargetting of difficulty makes the minority chain probably die technically. But it would be deadly if "original bitcoin" survived.
So no wonder miners are never forking away from the current protocol.
In my opinion, full nodes don't play any role in this. Miners are just locked in themselves, and it is only a huge agreement amongst them that will make them deviate from the current protocol. Whatever full nodes say.
There is something that is disturbing in this story. Miners HAVE hardforked in the past over block size. It was not so much in the node code, but when they increased the block sizes they accepted amongst themselves from 100 KB to 200 KB to 500 KB to 1 MB, these WERE technically speaking, hard forks of the *actual protocol*.
The argument that one shouldn't go beyond 1 MB, because this would harm the number of full nodes, and this would harm the decentralization of bitcoin, while if there's one number in bitcoin that doesn't matter in the power game, it is the number of full nodes, is disturbing, because that argument is simply wrong.
Now, IF you admit that that argument is wrong, and that a high number of full nodes are not a part of the decentralized power structure, then there is nothing that stops one from increasing the block size somewhat. Like it used to be done.
But this looks like kicking the can along the road. That's true. Only, nobody knows where the road leads to. It most probably DOESN'T lead to a global VISA-like payment system, and in any case that's not the problem right now.
As I argued elsewhere, LN is *probably* a neat invention, but it is a totally different trust model - unless you can EASILY settle on chain. If the chain is congested, LN sounds dangerous, much more dangerous than less full nodes that have nothing to say in any case.
LN can only be trustless and permissionless with a chain that can, without any doubt, absorb at any instance, all settlements, at any moment.So the block chain needs to have AT LEAST the full settling potential of the entire LN network. Proposing LN without an essentially unlimited block chain is totally changing the trust model that bitcoin users were used to. That doesn't mean that LN will not find its way. It can be fast, it is more anonymous in certain ways etc... But all this has still to be put into music in practice. It is a totally different way of transacting.
As such, using a bogus argument against potentially big blocks, and by doing so, not allowing the natural tendency that miners had, namely, effective hard forks increasing stepwise the actual block chain, causes fundamental problems:
1) it severely harms current users
2) it has killed the unity of miners, and has hence locked in the current protocol
3) it renders any eventual future LN not trustless and permissionless
4) if bitcoin doesn't really need much more room ever, because it levels off at a much, much lower point than "VISA levels", it has locked out the natural equilibrium end point of bitcoin.
All that in order to save a number of nodes that have no influence on the power structure in bitcoin, apart from "shouting out their preference" ; numbers that are easily manipulated by any big player in the field, BTW (Sybil) which was exactly why this number was made not to matter in the first place.