I am not a specialist of D&D 5e edition but it makes more sense for me that paladins should gain their powers from a deity. According to the deity, the powers should be logical ( I am thinking about a shar priestess well known here able to use fire and light spells...).

However, I thnk also that some deities should not have any interest to grant powers to any type of paladin.

Dans le doute, frappe ...