Coffee

I think there's a lot of fluff for sure. I do think there is some real technique to it, though.

Pouring so that you keep a higher volume of water in the pourover will help to keep the temperature stable, which should help keep extraction up. The two extremes here would be if you dripped water through in like 20 additions, letting the bed settle each time vs. doing it all in one addition. The average temperature throughout would be higher in the latter case.

Bloom should also have an effect for freshly roasted coffee. If you dump a bunch of hot water on really fresh coffee, a decent amount of the grounds will just float on top of bubbles, insulated away from the actual water. It matters less and less as coffee ages/off gasses.

Agitation should also have an effect. Things dissolve better when agitated; that much is obvious. The only additional thing to consider is that no coffee grinder creates perfectly uniform grounds. One thing that any beer brewer can tell you is that the "filter" is not what actually filters a wort from the spent grains; the spent grains themselves form a filter to get rid of any fine particles. Similarly in coffee, a lot of the fines will actually get caught up on the larger particles, provided the larger particles are allowed to settle. If you keep the grounds agitated the whole time, the fines will get sucked into the filter paper itself. Some will probably make it through into the cup, which could affect taste and texture, while much will clog up the filter, slowing the whole brew down.

It ends up depending on how good your grinder is (and if your beans are especially prone to making fines), and what type of filter you use. If you theoretically had a perfect grinder and beans, maybe you'd want to keep the grounds agitated the whole time, but if you have a crappy grinder, maybe you want to have no agitation at all.

Personally, I have an okay grinder, and i always use fresh beans, so I try to bloom my grounds with maybe 20% of the water, and agitate as much as possible. Then I add basically as much water as my pourover will hold at once, and I'll top it off gently as soon as room opens up.