Assuming you are not a troll...
UL is different for everyone. Some people with very light kits take along various electronics; not my cup of tea, but I am not going to criticize anyone for doing it.
A warm meal and/or drink is often a psychological boost for many people, or part of the overall backcountry experience they seek. A simple Esbit stove is going to weigh less than the water content in a single well balance meal of fresh or packaged food (not dehydrated or freeze dried).
For most people UL hiking is getting your weight as low as possible without sacrificing comfort or safety. Comfort and safety are different for each individual. For many people UL hiking is not about covering X amount of miles, or carrying Y amount of gear. People hike for just about as many reasons, as there are people who hike.
For ~ 3 day trips I don't always take a stove, but most of the time I do. There are times a stove does not fit into the hike, so I am not advocating everyone needs a stove. Whether or not they do take one is completely up to them. There is nothing wrong with the hiker who brings a stove and cooks 3 meals a day and even some hot tea or other beverage in between. Each person determines whether a stove or cooking is appropriate, and it is not up to anyone else to determine the legitimacy of how they hike.
How do you define trail running? Are you jogging or running? If running I would expect you could easily do 50 miles or more in 10 or 12 hours depending upon the terrain. If you are not doing this mileage, at a minimum, then I would not consider you a trail runner... but a jogger.
And as a runner, you could burn up to 10,000 calories in very complex nutrients in one day on a difficult run. Fresh vegetables aren't going to replenish all the needed nutrients, and as Tom mentioned, you are going to "bonk." When you bonk, you risk the chance of injury to muscles and other internal functions, exhaustion which can lead to mental errors that could put you into; a survival situation; or physical injury due to falls, sprains, or bad decisions. The amount of fresh food needed to properly maintain your body is going to push you well beyond the total weight a typical UL hiker carries on a 3 day trip, which means you are no longer UL. Don't look at the weight of the ultralight kit, look at the total weight of everything.
Yes, many people can survive for a long period of time without food. But many hikers are not into the sport just to survive, and if they get into a survival situation, then something went wrong with the hike. Most try not to get into these situations, although many here on BPL can take care of themselves just fine in most survival scenarios.