Is it not possible to do LN using full nodes (non-miners) that exist now, rather than "hubs?"
It may be entirely possible. I'm sure its possible with certain parameters, but no one has given a clear picture.
Suppose Alice wants to send Carol 5 bitcoins, through Bob. Alice has a channel with Bob, and Bob has a channel with Carol.
Alice->Bob->Carol.
The channels must be 5 bitcoins "wide" first of all. And both channels must pay fees for both opening and closing.
Alice and Carol can send money back and forth a gazillion times if both channels stay open and the amounts
stay within the channel parameters.
But if Carol needs her 5 bitcoins for whatever, and she closes the channel, then she has to open the channel with Bob
again before the transacting can go on, which she can perhaps no longer do because she is out of bitcoins.
Also, if Alice wants to send 10 bitcoins instead of 5, but Bob and Carol's channel
only supports 5 bitcoins, I don't think that is possible in a safe way.
So already there's complexity and we're talking about 3 people. You can begin to imagine that as the network of people
grows, you start to need more big channels that stay open.
So everyone ends up with a postal system, you have mail boxes, mail hubs, post offices, mail routes, prepaid envelopes, stamps, even spam.
Except it's much more complex, you have to buy prepaid envelopes for different destinations, sometimes you can reuse them, but sometimes you can't and what's left is wasted, unless you do a refund at certain time.
Usually when you build a peer to peer delivery system, you end up with something like TCP/IP, or bittorrent.
LN at the current stage is like the worst of both worlds. How the hell is it even suppose to work in a small country?
The only sensible thing to do is to make everything in between simple and free, then charge network usage bandwidth from end points like ISPs, that's the only way it'll be simple enough to work properly. If you keep doing accounting between nodes, the accounting database will end up being millions times bigger than the blockchain itself.
And I think that's why Blockstream is holding the lock on 1MB, they're trying to build networks and ISPs on top of Bitcoin's blockchain.