HeapTuple::get_by_index is not callable with array type

[semtexzv]

I'd like to read arrays from tuples, but the method bound requires T: IntoDatum, which Array<'_, T> is not.

Method signature:

pub fn get_by_index<T: FromDatum + IntoDatum + 'static>(
    &self,
    attno: NonZeroUsize,
) -> Result<Option<T>, TryFromDatumError> {

}

Is this just an oversight, or is there an underyling reason why this isn't pssible?