If the mix is coarse enough to have some open air channels despite the mix being saturated with water, air can diffuse pretty well down the whole depth of the root zone (the height of the pot). That's how natural soil works: the rest of the earth acts as a wick and lets the topsoil drain down to its "field capacity". Capillary force can wick water up from the water table into a "capillary fringe" whose depth depends on the fineness of the soil at that depth.
I think that any container is mostly "capillary fringe" or "perched layer" until it is dry.
I usually THINK I partly understand "perched water" right when I'm reading those articles, but then nothing sticks to my brain afterwards. So I must not UNDERSTAND it. But for some reason, it's only a problem in pots, not in the field. ???
Anyway, if the mix in the pot is so fine that water stays perched or held by capillary force to FILL most of the small pores in the pot, oxygen can;t diffuse through the liquid as it would through air. Gasses diffuse 10,000 times faster through air than through water.
So if your potting mix is coarse enough, the holes in the pot only need to let water out. The potting mix will then let water in from the top.
If your potting mix is fine and dense, with few pores in the soil larger than 75 microns, those pores will fill with water each time you water, and seal air OUT until the plant drinks enough to lower the perched and saturated layers below the parts of the roots you didn't want to drown.
However, as a plan, that's like a fraternity that decides to cram themselves into a phone booth and then have someone fill it with beer - they want to see if they can drink the beer fast enough that only a few of them drown.
Better to plan for your potted plants, or potted frat brothers in a phone booth, to have enough breathing holes that water and beer can escape freely, and then air can enter freely.
I always drill some holes in the sides of any tall pot, "to let some air in near the bottom". And to let the water out, for sure!
