Sometimes I'm told "this is an opinion, so you're not allowed to have your feelings hurt." That's like saying "I'm going to hit you on the arm, but I only hit you lightly, so you're not allowed to feel pain." The problem with harsh posts, even if they are just opinions, is that they still hurt, the reaction comes in any case, and it cannot be avoided.
From your perspective it may seem like "I'm going to hit you on the arm, but I only hit you lightly, so you're not allowed to feel pain." But from the other person’s perspective it could very well seem like “I feel pain when you engage in a normal and authentic exercise of your freedoms, so you need to constrain yourself to the point where I personally feel comfortable.”
Courtesy certainly has its place, but it’s not always admirable to offer it or fair to expect it. If I go to a restaurant with the intention to order pork, and I wind up being seated with a fundamentalist religious person at the table next to mine who would be offended to see someone eat pork, what’s the appropriate behavior? Should I forego a reasonable exercise of my own freedom just to avoid offending some stranger who chose to put themselves in a situation that might expose them to pain, or should I order what I want and let them deal with the consequences of their own choices and feelings?
Note that the calculation changes entirely if I’m inviting an anti-porker to dinner. Now the decisions by definition are around including the person and being mindful of their likes and dislikes, so I would be an asshole to invite them over and then serve pork.
And it changes once again if I’m going to be in an ongoing social interaction with this person, either living in the same home, or working together where we’re going to be eating meals in the same place. It would be unreasonable for this person to expect that no one else in the home or workplace should ever eat pork again, and it would be unreasonable for the others to think that it’s OK to eat pork in front of this person’s face all the time. Different compromises would be possible — people could do their pork eating outside the home, or warn the person when they planned to eat pork so they could leave instead, or they could eat in different places to avoid the issue entirely. If the anti-porker walked in on someone eating pork in a place where that’s allowed, they would probably need to suck it up, and if someone wanted to eat pork in an area where that was designated to be a no-no, they would have to avoid pork and deal with the disappointment.
The only thing I can think of is if perhaps thick-skinned persons might sometimes keep in mind that sensitive people aren't sensitive on purpose. And when posting about especially touchy subjects, like other people's favourite albums, to maybe leave the very extremely hurtful bits out.
The problem is that everyone’s sensitivities are different, and in different areas. If the solution is to remove all the edges that anyone might find particularly sharp to avoid hurting outliers, then you’re broadly neutering the conversation and you’re going to wind up with a 1950s sitcom instead of a 2020s HBO drama. Some people would love that outcome, while others would find it incredibly dull. Are the feelings of the people whose freedoms are being constrained any more or less valid than the feelings of the people who are hurt easily?
I would suggest a different solution. The forum rules define baseline acceptable behavior within the forums, and that should be the general standard, like what you’d expect from people in the public square. If people want to set up subsections of the forum or specific threads with tighter restrictions to be more accommodating to certain sensitivities, then people should honor those restrictions within those areas.
The GMAC is a sporting contest with voting and lobbying and winners and losers. It’s a competition and people treat it as such. If someone wanted to create a different thread where people just share albums they like with some specific rules around not making negative comments, I’m sure people would honor that, and the thread could be a safe space for a similar conversation without the rough edges. People who accepted those restrictions would participate, and anyone who violated those restrictions would clearly be an asshole.
Imposing broader restrictions upon general discussion is more like the anti-porker going to a restaurant that serves barbecue and then complaining every time someone orders pork. I would argue that the anti-porker is the one who’s being an asshole in that case, expecting the rest of the world to bend to their own preferences.
All of that said, I think you have a reasonable and self-aware attitude toward this whole thing, and I can’t imagine that anyone would post something with the intention of hurting your feelings. I certainly wouldn’t.