It is fact and part of business competition but without solid proof to accuse any competitors, personally it's better to avoid using it at any cost. Just focus on your own business, build it up from products to security and customer supports, then if your company provides good products and customer care, it will receive more support from users and will be able to attract more new users.
This is the way though reality is hardly that simple. People tend to believe rumors regardless of whether they are true or false which is why some unproven negative accusations against any crypto gambling site could make a dent.
Best way to deal with such stuff is to prove them wrong and nullify their pathetic attempts instead of completely ignoring them.