I have recently learned that apparently non-volitional verbs cannot have potential forms.
Non-volitional verbs cannot have potential forms. This includes verbs of natural phenomenon like 降る, 光る, 流れる, and 凍る, those concerning human emotion and physiology (痛む, 痺れる (to be paralyzed), 羨む (to be jealous), any verbs that end in ある (as they have no volition), and any pattern that has no control involved like phrases with つく and いく such as 想像がつく (one can imagine) and 納得がいく (to accept as valid).
So 光れる and 凍れる for example are not valid conjugations? Is this invalidity strictly a structural limitation or is it semantic?
For example, I feel like "able to shine" or "able to be frozen" are reasonable concepts with semantic meaning. What about rephrasing as 光ることができる or 凍ることができる? Are these ungrammatical as well? If not, I don't see the problem with the potential form.