Bitcoin was born into a unique environment. The world did not know what to think, and largely ignored it, so it was able to spread organically for years, detached from any notion it would ever be worth anything. Because it had no value, it could grow without having to worry about these kinds of attacks. Only once it spread far enough did it begin to take on economic value and an exchange rate, reaching one penny and beyond.
Airdrops these days do the exact opposite. They're premined, listed day 1 on exchanges, and the creators try to pump the exchange rate in order to finance later development. The entire process is corrupted by users viewing projects through an economic lens, and creators trying to extract value before delivering value. Now that the cat is out of the bag, it's likely the conditions of bitcoin's creation will never happen again.