when you say "in my opinion" it means "subjectively, you're incorrect".
that's why we use "in my opinion" because for some things there's no objectiveness.
of course it makes sense.
what is an opinion? an opinion is a personal belief or judgment that is not founded on proof or certainty. thus it makes perfect sense for the opinion to be subjective therefore i can say what's right to you is wrong to me because we seen in 2 different directions.
which is the standard that will tell us which of our opinions is right or wrong? - there's no standard. that's why i said : objectively you can't say incorrect. subjectively, you can.
IIt makes sense to tell somebody that their subjective opinion is wrong when they base it on objective information that is wrong (ie. misonformed), or, when it is wrong in reflection to the majority opinion (even though that too remains subjective it is granted consent/clarification by numbers, so it too is not necessrily right).
what you say is true, but [in one of the posts you quoted] he mentioned "by nature" which means, because of the nature some things are absolutely true.
like the sunrise. it's not a matter of opinions. it's a matter of facts.
while when it comes to opinions, there's relativity.
so he contradicts his posts. he mentions "by nature" and then mentions "opinions".