That particular poster also posts here under another name and has shown that he does not even know what country he lives in. Maybe he cannot get 1.0mm cheaper than 1.5mm but I have never come across that problem.
There were other reasons given for using 1.5mm² including, as I said, versatility.
Do you honestly think that anyone who reads the thread you linked to is not going to see those posts, and is going to agree with your interpretation, or is there actually something wrong with you?
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