I'm sceptical it matters much, except for pre/post workout meals.
I've been told it's important by more experienced and educated people than me, but I've not seen any evidence for it, neither anecdotal nor scientific studies.
The only issue seems to be if you get some protein and carbs into you immediately before a workout to fuel it, and immediately after it to help recovery. Doing that seems to give you better gains than meals further from the workout.
It does seem that for people who want to change their body composition, having several meals instead of a few is better - psychologically. Those who want to get smaller can feel full all the time with lots of small meals. Those who want to get bigger and find it difficult to eat enough can eat several medium meals (instead of three huge ones).
I think it's also the case that if a person has just three meals, they might eat just whatever. But nobody can eat 6 meals a day without preparing most of them. And when you prepare your own food it's likely to be better for you, you're more conscious of what you're eating.
But I've seen no evidence for it being a physiological thing. Most food takes 5-6 hours to pass through our body, and most nutrients are absorbed in the intestines, just before it's turned to poo. So the idea that we turn catabolic and start eating up our own muscles shortly after a meal or overnight and have to have a constant drip-feed of protein is obvious nonsense.