I don`t remember having airdrops for my BTC balance until 2017. Why did they not have any before? What changed in the system?
There were a lot of airdrops before 2017 as well. But since the price of BTC was not that high, people were not much bothered. Check this thread, for a list of airdrops from 2016:
https://bitcointalk.org/index.php?topic=1438371.0And if I am not mistaken, the first crypto airdrop was in 2014 (Auroracoin).