My mother always taught me that compost teas do many things. They can inoculate a substrate with beneficial bacteria, fungi and other microbes (the break down organics to plant available nutes). They also feed the plant directly, through water soluable broken down nutes, as well as feeding the current and future population of microbes.
I’ve used synthetic nutrients in a peat/coco/perlite soil that was amended with organic nutrients. I may or may not have “ideal” levels of microbes, but since I also use tea, there is always more being added. It’s definately working.