I saw some examples of projects which developers thought that it`s enough to start trading contest and their coin will be popular and will have really good price, but it`s definitely wrong. Trading contests really good opportunity to attract some more attention to cryptocurrency, but I think that it should be secondary way of increasing volumes on pairs and boosting token`s price
it is basically pure marketing, that is in favor of exchanges, since trading on particular coin/token will rise, but at the end, without workable product and good development plan, no trading competition would make some coin useful, so it is good for a start and to get visibility, but project development and idea are the basic of token value, this would just add customers to it, which is important step, but could not make it on its own