"Turning soil upside down" is ploughing (plowing) with the machine with same name. The machine in the photo is used to destroy the clump of dirt (and with a light mix of dirt).
So there are two different machines. Ploughing is useful for new fields and for fields with "green manure". The green will be put on the botto, so it will create manure. But such huge change of soil is dangerous if there is not many inches of organic soil: you put on top the mineral part and on bottom (not reachable by vegetable roots) the good organic part.
"Your" cultivator requires a already prepared garden. It is ok if you cultivated it the previous year. It also requires not much green on top: read: remove as much weeds as possible.
For microorganisms: I'm not so sure. Vegetable gardens are not so huge, so there is many boundary effects, and we does't use it on all vegetable garden: some part are seeded in fall, some in different part of late winter and spring, so I don't see a huge disruption. Additionally, manure will also change the microorganisms (pH, a lot of new organisms).
Personally I find some disruption good. Many diseases are specific to species (and genus) and good organisms are all-arounder (not really so, but I think a good approximation). So disuption will help to kill some unwanted organism, but the other organism can walk in (from the other patches and borders, [containing other genre of vegetables]).
So I use it (a very old machine) or I do it manually.