I think one problem that people experience with "dirt" or "field soil" or bagged "potting soil" is root rot.
Not only the particle size, but the material that those particles actually are, will determine how much water the mix holds.
You see more conversation about inorganic vs organic material for soil mix, than about particle size....both are very important however.
In general, organic material holds more water.....and the smaller your particle size is, the more water it will hold.
The asterisk goes next to the inorganic mixes, because there aren't any nutrients in there for the tree.....that's where fertilizing comes in.
I personally prefer lava and pumice with a good layer of sphagnum on top....I also like DE, Haydite, and Turface as additives.
This year I'll be trying a bit of Fir Bark chips in with my lava and pumice....
Soil mix for bonsai will differ depending on your microclimate, and ability to water....
For example, I moved in 2018, in June.
My old house had many huge beech trees and poplars, shading the area for most of the day, and watering was not a problem, just morning and evening.
At the new place, I'm on top of a ridgeline, in full sun....and I'm farther away from work, so I don't get home until later, sometimes I'll be out from 5am to 8pm, and when it's hot and breezy, my trees dry out fast.
That's one reason why I will be experimenting with adding bark to my soil mix this year, for more water retention.
As well, I'm going to be using a thick layer, at least one inch of chopped sphagnum moss on all the trees that need it.....that sphagnum on top can be all the difference.