It is granted that fiat is generally brought into creation by borrowing against a balance of zero by central banks across the world. While people may compare this to a fork situation where seemingly an entire new concurrent stream of cryptocurrency based on the principle is created, I think that there are many differences.
First, there is a total of just over 200 currencies around the world, while there are already 1000s of different cryptocurrencies (imagine 1000s of different forked versions which are forked further). Secondly, when a currency is borrowed against nothing (with certain exceptions) the currency depreciates Sharpley in value. It does not increase. Theres no way that our governments can announce that we all have an equal amount of new currency based on what you had at the time of announcement and expect it to be valuable.
Cryptocurrencies should face the same market forces. While people may view Bitcoin cash as valuable and as it stands, it seems that a correction did not happen, the cryptocurrency community should treat forks of coins with the contempt they deserve. When BCH was created out of thin air, its value should have been 0.001$ but instead, the market valued it at $700 and now its about $300. Holders of bitcoin were rewarded new valuable currency as though it were largess. The next cryptocurrency fork should be treated harshly especially if its a further BTC split.
This issue of forking must be addressed if cryptocurrencies are to become as accepted and understood as fiat.
It is the market which attributes to different forks. Bitcoin Cash does have significant backing and actually split the bitcoin community. So it would be wrong to attribute 0 value to it. Bitcoin has risen post the split. That does not take away anything from Bitcoin Cash.