Not always, i do not agree with this assertion, ico investors also dump tokens at will especially when enormous bonus are given to sell out ico an example is seal investors were given 370% bonus tell me why price will not dump.
It is not good to forbid people to dump their tokens, but it is also not good when people dump their tokens all at once.
Lympo had good token distribution. The distribution took place trough several weeks, so they didn't send Lympo tokens to all people all at once.
This was very good move, because it stabilized the price. Who wanted to dump the tokens they could dump, but it didn't affected the price very much, because bounty hunters and other could sell tokens only after they recieved them.