Is mold really that bad ?

About 4 months ago i setup my first terrarium, and a month ago i made a mistake using silicone, and the acetic acid burnt all my plants leaves. All the dead plant matter started molding, it spread to the soil on some spots, but i left it alone.

Now, i have a boom in springtails and in my two species of isopods, i constantly see them on the parts were theres mold munching on it. Even better is that all those dead parts made new leaves, and my plants are much denser so it looks even better than before.

My question is, why is everyone so scared of mold ? I keep seeing posts about it, but in my experience it was very beneficial