1. The original post did no exclude the possibility of a land tour. Many (maybe even most) people incorporate a land tour in a 1-way and in fact some here recommend considering RT if not doing a land tour. More to the point, one of the previous posters made this same assumption and provided advice accordingly and about how doing this post-cruise is a bad idea. And Karen's post mentions her preference for Seward over Whittier, which is only relevant if a land tour happens. At very least, it would probably be good to give advice in a way that highlights landtouring pros and cons in case the OP is considering it. I think giving the opinion for a particular direction on a cruise-only is great too, just don't understand why its wrong for others to give enough information in case the OP is or might consider adding the land tour as well.
2. As for the "myth" issue. I don't have my copy of Webster's handy, so I can't directly respond to whether opinions might never be labeled myths. But why do you think that comment was directed at you? The N/S issue is raised a lot and you typically get a lot of the same responses with the predominant being relax on the southbound trip because the land tour is so exhausting (I realize this brings up your concern that the OP does not explicitly state a land tour, but I'm just hopeless so ...). I think that is a myth perpetuated by numerous travel agents I've spoken to and by many on various boards that stems from the fact that they do a short land tour. I don't think people should buy into that before learning anything about what they want there Alaska trip to be like. Now it is entirely different if someone holds the "opinion" that it is nicer to end with a cruise because you can go to the spa everyday and eat endless good food which will always be more relaxing than a land tour that involves any amount of driving, but that's not the normal thing you hear on this issue. Or for someone to appreciate that short land tours are not advised and that if they insist on doing it, southbound may be a better choice. I certainly don't debate whether people are entitled to have an opinion on whether they prefer (a) seeing glaciers at the beginning of their trip or (b) they would rather let the anticipation build over the course of the vacation.
My post very clearly begins and ends by noting that there are different opinions on which direction is better and that there are pros and cons each way and that it depends on the individual's style. I even mention that others have cited the same criteria that I mention and consider it better fullfilled by going Southbound and I raised at least one pro-South reason not mentioned previously and echoed a pro-South reason offered by Karen.
Guess next time I will just say "North is better."