Yeah I started being more observant of this stuff recently. The only way to gain weight really is by consuming lots of fats, refined carbohydrates, or by drinking your calories. Ultimately it's still calories in minus calories out, but those things are where the calories are.4 cups of rice and 20 oz of chicken (split up at 4 meals) is 800 + 1000 kcal total.
Add some fats here and there like olive oil, but you're still barely getting 2000kcal with a high volume of food. (Vegetables and fruit are so low caloric density I really don't count them unless I'm eating like 2 avocadoes)
So for me if really active and not trying to lose weight, it's 5 oz beef/chicken and rice/potato x 4 a day + a 500 kcal shake and I'm hitting 2500 kcal... And I may add another meal of meat/eggs on top of that to get it up to 3000kcal on leg day.
If I'm trying to lose weight, it's the above, but one of those is a salad with no carbs.
That's a lot of volume of food. Most people are not actually logging their macros and haven't been doing it long enough to know what's in a meal.
If anyone is struggling to gain weight and you're drinking water for every meal, just try replacing that water with whole milk. I put on 30 lbs in about 3 months once largely through drinking lots of milk. Of course most of that was fat because I bulked too quickly, but the point stands.