The examples of hideously intense toxicity described in the OP are obviously completely legitimate. Unfortunately, barring some completely miraculous development, people that express that toxicity will always be present in some quantity. Moderation is the only solution against these people, they must simply be allowed no place in the discourse. But as the OP describes, these people are outliers. The reason discussions surrounding the Epic Games Store have become as generally heated as they are is different.
That reason is that what Epic is doing is unethical, full stop, and moderation here has been too lax on this issue. I'm going to quote myself here:
There really isn't anything to argue about with the Epic Games Store. The exclusivity agreements are its sole defining element. The revenue split isn't industry leading, and beyond that is moot because Epic's statements and practices have revealed that it's unsustainable for them. Their curation practices are essentially a match for where Steam was a decade ago, and have the same issues. They've suggested no effective means of solving those issues. The store's broader featureset is uncompetitive. Without the exclusivity agreements the Epic Games Store would simply be a quiet failure, there would be no discussion of it at all.
Everything comes down to whether you find the practice of buying exclusivity acceptable.
As to exactly why it's unethical, I can get into that if we really need to, and did a bit in the post I quoted, but since we're trying for a saner conversation here let's just take that as given for now.
We have no real power over Epic's course of action, or the developers and publishers that sign on with them, so we can't truly solve the problem, but we desire to lower toxicity here. How do we do that? Let's start by looking at the nature of these threads by describing the posters in them.
There are essentially 6 categories of posters arguing in these threads:
1. Those that see the exclusivity practice as unethical, and argue against it
2. Those that don't see this practice as unethical, and argue for it
3. Those that see this practice as unethical, and argue for it
4. Those that see this practice as unethical but support Epic for other reasons, or claim to
5. Those that see this practice as ethical, but don't support Epic for other reasons
6. The broadly uninformed that have nonetheless formed an opinion
The first category is completely reasonable, unless it gets into toxic territory.
The second category consists of people that are either somewhat uninformed/misinformed, misguided, or both. The best solution for them is a combination of a direct and detailed statement of the facts in threads on this subject (a mod post) and ongoing moderation in-thread with a low tolerance policy for those who ignore the facts in the mod post. The existing statement on threads on this subject is insufficient.
The third category consists of trolls. They do what trolls do: build toxicity while generally being careful to never cross the line into obvious expressions of bad faith, exploiting the inability to distinguish between people that truly believe in what they're arguing and people that don't. In reality it's rarely all that difficult to distinguish between the two, and what trolls are really exploiting is soft moderation. Obviously then what's needed to deal with them is (much) stronger moderation, again with the statement of the facts as the base for justifying moderating action.
The fourth category has obviously spurious arguments and consists of more trolls and people who've been duped. Moderation can be less harsh on them unless they're suspected of trolling, but they should be reminded of the facts.
The fifth category is weird, and effectively similar to the second. They're tough to moderate, but aren't very common. Again, remind them of the facts.
The sixth category is problematic whether they're arguing for or against the subject, but they tend to move with the status quo, which in this case is with Epic (these are the genuine "I don't know why people are so heated it's just another launcher" people). In that case their effect is the same as those who are knowingly trolling. Once again, an ignore-at-your-own-peril statement of the facts and strong moderation are the solution here.
If those solutions seem repetitive, you're right. If they seem similar to what's already in place, you're right. The difference between a toxic environment here and a better one is actually pretty simple, it just involves accepting some harsh realities: that what Epic is doing is unethical, and that moderation hasn't been good enough in standing against it. I'd also say that those posters in the first category that take clear stands and write detailed, relevant posts deserve more leniency. There have been instances where really excellent posters have gotten a bit heated in these threads and been banned, sometimes for rising to the bait of a troll. This is really unfortunate.