Credit allows to get a probability of how likely it is payments get done. Landlords use it to get a probability of how likely payments will be.

In your case, they don't have your credit, so they obtain the probability through other variables, like your income. Most likely they'll assign a high probability to you paying, but the confidence interval mat be too big for their liking.

Obviously credit history doesn't give zero information, which is implied in this thread several times.