Joseph – although explaining yourself may not make a difference to certain ignorant (and possibly even ignorant that they are ignorant) and/or Halacha-denying posters, sometimes a little explanation can make a difference to a different innocent poster who is willing to follow a psak of poskim, and would benefit from an explanation. Not that poskim have to explain themselves – anyone denying the correctness of Halacha because they don’t agree with it may be an Apikores. No explanation is required. But where an explanation is available why not provide it.
Here is one scenario explained:
If a merchant sells a product and makes his living from it, and once in a while you get a product that is ‘less than you anticipated’, your Halachic recourse is only to get a refund. Once the seller has refunded your money, he has satisfied all of his obligations to you. Even if he DOES NOT give you a refund, you would only have a claim against him (in Bais Din) for the amount of your purchase. Posting a bad review online however can (and unquestionably will) result in hundreds or thousands of dollars in lost revenue, far exceeding any claim you may have against him. The damage you do to his business will continue to accumulate forever.
Most of the time we are not dealing with an outright thief that is perhaps advertising a non-existent product and purposefully ripping off all of his customers. If that were the case, other (non-Jewish?) reviewers can be relied on to warn you and others. A situation where your review is absolutely needed to protect future Jewish victims from being robbed is unlikely and maybe not what Joseph was referring to.