>>10073126It is hereditary. Some people are naturally more prone to having the edges of their nails curve down at the sides, and so need to be more careful about cutting them too short or leaving a jagged edge at the side.
>>10073214That inflammation is due to the nail cutting into the skin, which is never a good thing. Inflammation is naturally caused by infections and doesn’t need help forming preemptively; the nail is only opening another avenue to infection rather than protecting if one occurs.
And a nail curving down at the edge is in no way protecting the exposed nail bed if a nail tears.