Indeed, and we can expect just as many customers of the competitor-cruise line will have had a similar experience on that cruise line and out of spite intend to take their business to Holland America. A certain percentage of custom in the mass market will always be in churn. It is too costly to make mass market products and services so perfect that such churn is eliminated.

Of course. All the major mass market cruise lines are comparable to each other - none significantly better or worse than any other. They will vary with regard to individual aspects, but in the overall they'll have roughly the same amount of positives and negatives as each other. I typically recommend that people not do as the OP says he plans to - do not switch providers because of a bad experience that is, in reality, the same experience that you are as likely as not to have had on some other cruise line. Rather, learn from the experience - learn what is reasonable to expect, yes, but more importantly learn the ropes of customer service of that one cruise line. Even though you do not get satisfaction for your initial grievance, you've now got names and numbers and a story to tell the next time something doesn't go as you wish. You also have points toward elite status that might make a difference the next time.

One significant exception to that: If your intention is to "uplift". Perhaps what the OP has learned from this experience is that the mid-market mass market cruise lines don't offer the quality of service that he desires. The luxury cruise lines perhaps do. CCL offers Seabourn for this very reason - a luxury cruise line that offers that more rarefied level of service, superior accommodations, few if any staterooms with the kind of serious compromises that the OP encountered on Koningsdam. Switching to a better class of cruise line makes a lot of sense, if you can afford it and can justify the added cost.