The way i figure it.
Is its mulch.
We use mulch outside to insulate our roots. Yes definitely.
But its the thermal heat from the mulch, keeping it all healthy. Imo.
That thermal heat is coming from the beneficial bacteria feeding off the mulch.
The microbes are having a field day.
Green matter, is breaking down.
Rain or water comes along, and washes down this "tea". Thats teeming with bennies.
Imho making compost tea. Is just making the tea without a mulch.
Just my opinion, anyway.
I'll leave it there.