It's a sliding scale, basically.

At one end you've got unsupported crankery at its worst.

Somewhere inbetween you have opinions that can go from stupid, to considerable, to very well-supported and almost inarguable. Those opinions can and SHOULD be backed up, and can be stupid or smart, right or wrong, for all intents and purposes.

At the other, proven, backed-up facts (even though even those have different degrees of certainty; like the validity of a paper, or statistic).

Not sure whether you can call logical absolutes "facts", but the rules of logic (like why all the fallacies are fallacies) are pretty much up there as certainties, as well.
So if someone makes a clear logical fallacy in their reasoning, they can be called "wrong" even if they weren't talking about any physical facts supported by statistics or papers.

Basically, an opinion CAN be "promoted" to a fact, or rather, "pretty damn certain knowledge", it just needs good evidence.
Making a prediction that if I let go of my pencil, it'll drop to the floor, is a fact; weather or medical predictions are "probability statements", or professional opinions, and some shaky, disputable suggestion how to improve one's finances, an opinion.

So that's it in a nutshell.
Obviously, none of that applies to the second main meaning of "opinion" (also in that same dictionary), which is basically personal taste, and can't ever become a "fact".
We may all share similar patterns of perception, to the point that someone can be reasonably called "blind" for not perceiving some kind of beauty - because they probably would have the potential to perceive it just like the other person - but in the end, a sunset isn't "beautiful" except in the mind - it just is.

That's the kind of "opinion" that needs no "backing up", cos it's a "fucking opinion", and can't become an objective fact by definition.