The project is old that is why community is so big. Now cryptocurrency market raise and a lot of people pays attention to cryptocurrency. Airdrop is good to attract attention of the crypto community to the project.
A lot of projects now conducts airdprop. So users have a very big choice and it is still diffucult to attract attention of users.
If project is popular and perspective it will be able to attract a lot of users during airdrop because now cryptocurrency is very popular.