Because I've used it as an "or" symbol in a non unique common as muck manner since 1980 at least when I was taught Boolean logic in an undergraduate university mathematics class.
It's one of many conventional symbols for OR, more common in the pure ASCII days due to a lack of ∧ , ∨ , ¬ et al.
Which rock have you lived under that you've never seen it used an OR before?
People imposing their limited experience of the wide world upon others would certainly irk some, but rest easy, I've not taken offence at your odd assumption of non existent universal convention.
It's one of many conventional symbols for OR, more common in the pure ASCII days due to a lack of ∧ , ∨ , ¬ et al.
Which rock have you lived under that you've never seen it used an OR before?
People imposing their limited experience of the wide world upon others would certainly irk some, but rest easy, I've not taken offence at your odd assumption of non existent universal convention.