Running a small little research around here. For example, Bitcoin has (or will have) a total of 21 million coins, tops. Litecoin seems it will have up to 84 million coins, total.
In your opinion, when a new altcoin is created, how many coins is just too much? I have seen projects with like 10,000,000,000,000 coins. That looks almost like... a spam coin :/
A project however good that may look should not have billions of supply, I have seen good project with very large supply that struggle to make demand on their coins because to many people are dumping it, even if there are projects and platforms to offer the modest supply should be 300 million.