One of the resultative way to attract a lot of users to the platform is bounty and airdrop. It is a good opportunity to get a free tokens for participants.
After the start of listing many bounty hunters and airdrop participants start to sell tokens. It affects to the price of the tokens.
You can't avoid the dumping stage on each and every project. Those who are solid and strong enough can fight this battle. But those hunters will at least give trading activity at the start. Now, it is up to the team how they will sustain the activity afterwards. They need to have contingencies on how to address such situation.
Because of dumping stage some investors prefer to buy tokens not during IEO but after the lisiting on exchanges.