That's all fair, I am definitely not the best educated on this myself. I eat the way I do because I have found that:

1. It satiates me. Satiation is critical to avoid overeating. Having veggies and rice with a smaller meat portion at dinner, I don't want dessert as much. If I have those leftovers for lunch the next day, I don't get peckish in the afternoon as often. And if I do (like these days since I've gotten back to exercising in earnest), I pull out the pistachios and eat a handful and I'm good.

2. Setting aside exercise, I am consistently at a healthy or at least healthier weight eating this way. If I eat like this and avoid candy and soda, my weight is under 200 without any exercise and more often around 190. On my frame, 180-190 is a healthy weight and 190-200 is an ok weight (it's a healthy weight if I'm doing strength training, but I don't do that anymore so it's too high but not awful). If I exercise regularly, my weight will reliably be between 180-190 (190-200 if strength training).

3. I physically feel better eating this way. Less sluggish, better sleep, more energy when I do exercise (which is regularly these days, but hasn't always been). And all of that also leads to an improved mood (which is very critical for me as someone whose had issues with anxiety and depression).

4. Every health metric is better for me at this weight, again even before exercising (with exercising the numbers improved even more). My blood pressure dropped from 135/?? to 110/?? (forgot the bottom numbers presently, it's in my records somewhere). My cholesterol dropped from 250 to 150-180. My A1C (blood sugar) measurements went from "prediabetic and almost diabetic" to normal (I've forgotten what the specific numbers were).

5. It's inexpensive if you're willing to put in the time to cook and can find a good store with good prices. In the US Southeast I found Fresh Market to be a great source of everything I ate except rice (prices were too high). Their produce, meat, nuts, and cheese prices were as good or better than the big chain supermarkets. I went on Tuesdays when they sold chicken and beef for $2-3/pound (versus more normal $5+/pound prices).

(2-4) should probably be first, really. Those are the primary reasons why I have tried to maintain this approach to eating over the years. Diet and weight have a major impact on quality of life. What diet works for you, though, I don't know. Try some things out, find the metrics that you care about (for me: sleep quality, energy during the day, those various health metrics) and see how the diet impacts them. You can experiment on yourself. Try different diets (and exercise routines) to find things you like and can stick with and that improve those metrics you care about. I have read up on a lot of nutritional guidance and exercise guidance because I use that to feed into my self-experiments. A lot of it seems contradictory, it's annoying. I don't care. I tried various things until I got into my current approach because it works. I continue to do it because it has continued to work (for about 9 years now). If some advice or guidance seems obviously misinformed (eat only meat and cheese! embrace the gout!), don't do it. Otherwise, if you're still hunting for ideas that work for you and you can sustain, give it a shot for a few weeks, worst case you get nothing from it or feel a bit worse for a short period, then you drop it and find something else or go to your old routine.

I feel better, my health metrics improved, and I'm able to do the things I want without struggle, then it's working. If one or more of those weren't true, I'd try something else.