Except your clone doesn't have miner support, community support, and get listed by major exchanges. I hate that people are acting like anyone can just go and make a fork for free money.
Oh, but they can. Here's what this whole drama has proven:
Any one can fork a coin. Then attach a significant market value to the given fork by promoting it heavily. Or if required they can do it after the fact - They can be on the buy-side and creating an ever increasing bid to pump the fork.
As for the support, you will have human greed play a big role. Everyone holding x coin gets 1 x coin + 1 fork coin with significant value which means it will create some market as well as intice miners to mine a coin with much smaller difficulty.
I'm not sure what you're saying here. Are you claiming that Bitcoin Cash doesn't have those things? Or are you saying that those things are important factors which differentiate Bitcoin Cash from other forks?
"Nothing stops me from just announcing that I've cloned a copy of the bitcoin blockchain for BCM"
You can't just make random forks and have them be worth something. This is the culmination of years worth of debate and has a significant community following.
You're (understandably) confusing a code fork with a chain fork:
Code fork: taking the source code from one project, modifying it, then offering the result as a new project. This is what the overwhelming majority of altcoins are. For example Litecoin is a five-year-old code fork of Bitcoin. Even though Litecoin's code is nearly identical to Bitcoin's, Litecoin from the beginning created its own blockchain, which shares no data with Bitcoin's blockchain.
Chain fork: taking the blockchain from one project, and adding new blocks to that chain that are not compatible with the chain's original style. Variations of this are soft forks (the block-adding rules are made more strict), and hard forks (the block-adding rules are made less strict). Both this week's BTC-BCH fork and last year's ETH-ETC fork were hard forks.
Complications: obviously, a chain fork requires changes to the relevant code to be able to work, so a chain fork usually comes with a code fork, but not necessarily. For example, theoretically, a completely new code base could be created from scratch in a clean-room kind of environment to add new kinds of blocks to an old blockchain.
Before Bitcoin Cash, all (afaik) other alt-coins weren't based on BTC's blockchain history. Ethereum, for example, raised development money by selling off the early coins on the chain.
It isn't done often because it's not seen as a useful technique mostly: you just gave a ton your asset to people who think it's worthless, and who may actively dislike it. Not a great way to maintain a market price.
If you don't share blockchain history, then you don't automatically get some of the new coin by holding some of the previous coin. So there are no issues with exchanges and shorts.
Also if you do share history, it is much much harder to start, because you start off with the previous difficulty which is very hard to mine on. If you start a new altcoin with a clean history, the difficulty starts off very low.
Bitcoin Classic and Bitcoin XT have not actually forked the blockchain. So they are not separate coins yet.
Not really. It's 1 mining pool with maybe 1-2% of the total hash rate of bitcoin. I'm not sure it has significant community following or backing. I suspect the majority of the community would have preferred not to have the confusion in the market and avoided the split entirely
The point is, what's the threshold for "enough support"? Already for Bitcoin Cash, different exchanges have come to different conclusions on whether it's sufficiently supported to list on their exchange.
There is no threshold, it's clearly a gradient. Some exchanges want to list it, others don't. Certain exchanges listing it gives it more value than others, and if it's impossible to trade/spend, then the coin has 0 value.
Any one can fork a coin. Then attach a significant market value to the given fork by promoting it heavily. Or if required they can do it after the fact - They can be on the buy-side and creating an ever increasing bid to pump the fork.
As for the support, you will have human greed play a big role. Everyone holding x coin gets 1 x coin + 1 fork coin with significant value which means it will create some market as well as intice miners to mine a coin with much smaller difficulty.