It's funny, that's how things should work, but the crypto space has been so irrational it is not how things have effectively been priced in other splits. For example, Bitcoin Cash's split ended up being free money for consumers, which doesn't make sense in a rational market. Bitcoin Cash split from Bitcoin, but Bitcoin actually maintained value (and went up soon after). I'll wager most of these will have little affect on the price of Bitcoin. Often, the bigger issue is that no exchanges offer pairs for the new Bitcoin forks, so they're basically useless.