More and more new coins adopt the AirDrop system, as more and more investors are quite reluctant to invest in ICOs, given that in 2018, just a handle of coins/tokens has been able to maintain their pre-ICO prices. Most of the investors are losing money right now with 2018 ICOs.
Thus give them a working and functional product through Airdropping, and they will give value to that coin, for example through trading contest, or through holding contest.
It reduces risks for investors, because they can test a functional product before investing, and it's less a game of gambling as it is with ICOs.