You can see it by the chosen category, this is real oil color because the category is Traditional, and if you then search for the category description, that is always a posting after the scheme “About the XYZ category”, so here “About the Traditional category”, you can read what the category is meant for → no “digital artwork” in this case.
But of course you can imitate oil paintings with Krita, just use brushes made for that kind of painting.
Michelist