The bitcoin when it was born was distributed for free then with time it gained value, there were no other projects, then as theBitcoin has grown in value, many other projects have begun, many of the projects were born to scam investors, for me all new projects should be distributed for free.
A few years ago I joined one of the first successful airdrops for free, the project was Decred, coins were sent to 3.000 holders and it became a profitable coin. Most projects that came later, unfortunately, preferred the ICO formula: a much faster way to make fast money than giving away your coins/tokens and hodling for months or years until they gain some value, but that showed to be prone to abuses by Devs and team members.