I see you're familiar with the "danger zone" concept. I think the only on-topic way to answer this is to help you add up the "danger zone" time, (and raise the concern of cross contamination!). I will say in response to your heading, there is no "loophole" in food safety guidelines. They are pretty stark in that things are either safe or not.
Eating something that has been treated "unsafe" aren't guaranteed to make you ill--but for this site, "will it make me sick?" is off-topic, while "is this considered food safe?" is on-topic, so I'll focus solely on the latter.
Cross contamination ❌
It's not guaranteed this will happen, but every time you handle something, you risk cross contamination. Uncovered food in the fridge can also be a contamination vector. Each time you reuse a dish without washing, you essentially double your chances of having a problem. A trace of e. coli on an apple peel during breakfast has a chance to be transfer to the plate, grow all day long and be ingested during every meal of the day, increasing the chances that you might get ill.
Danger zone math ⚡
Keep in mind that this is a CUMULATIVE time for the food (and residue)--it doesn't reset when the food hits your bowl. Also, food safety guidelines consider a plate to be "contaminated" with food from the time food hits it until the plate is properly washed/sanitized (ie, with soap). Even if there is no visible residue, if it hasn't been washed properly the plate is treated the same as if there was still a full serving of food on it, from a food safety perspective.
Based on all of that, you'd need to add up time the ingredients (for everything that was on the plate) are unrefrigerated coming home from the grocery, being prepared & cooked (between cold and hot), after cooking on your plate, time in the fridge while cooling back down, repeat for each meal.
If you use the same plate for breakfast, lunch, dinner, and dessert without washing, you'd essentially be calculating the danger zone time as if you had breakfast leftovers that you refrigerated then reheated at lunch. Then added extra lunch leftovers and put them in the fridge. Then you reheated breakfast and lunch leftovers, added some dinner leftovers and back into the fridge. Then reheated breakfast, lunch, and dinner leftovers to eat them for dessert.
So it gets complicated to do all that math... But there's a lot of time that will accumulate as it passes from warm to cold to warm to cold, etc.
My verdict? 👨⚖️
It seems unlikely that you'd be able to add up all that time in the danger zone and still stay within the time window that is considered food safe by government food safety guidelines.
If you're already going to rinse it water to remove visible residue, a quick swipe of a soapy wash cloth seems like a low-difficulty added effort to wash away the remaining unseen food & bacterial residue. I'd even possibly argue that a quick soapy wash is no more difficult than trying to find a way to stay within food safety guidelines.