No. Because opinions are preferences, whereas arguments are based on reasoning. That can be sufficient or insufficient reasoning to convince someone, but calling acceptance or refutation of an argument an "opinion" is seriously misusing the term.
When presented with evidence that is not convincing, you need to say why it's not convincing; what questions doesn't it answer, for example, or why is it logically incoherent. Or any number of other DISCURSIVE objections that aren't just "well I guess I just have a different opinion!".
You said you have a background in history; surely you must have encountered this kind of debating practice in the field.
But not because of their opinion, but because of the evidence presented. An opinion requires no evidence, and can't be refuted by evidence.
In fact, most people will retreat to opinion to AVOID engaging with evidence. That's why so many people believe Jesus existed NO MATTER the evidence for or against it.
You're trying to conflate argument and opinion here to obtain license to dismiss claims for evidentiary substantiation. Opinions are conversation enders. If all you wanted to say is "I believe mythic is ruining WoW, and I'm not interested if that's actually true or not, it's just my opinion" then what was the point of all this? Just getting your voice out there and heard, and have people go "yeah, that guy over there, definitely got an opinion, that one"?
Opinions are useless in discourse because they don't have to obey any discursive rules. They're of social and personal interest, but in arguments they're utterly without substance or meaning.