I am all for a robust discussion.
The PA31-350 POH actually permits LOP, one of three options for leaning, so here we might even agree. However, the actual Lycoming engine manufacturer does not approve LOP.
The Continental service bulletin cites engine longevity as an issue when describing LOP, and recommends this only in extreme long range operations, and only occasionally.
I should add I have absolutely no engineering quals, and am usually wrong with most things.