Since soil fungi aid in digesting the organic matter in your soil why would you want to kill it?

"Since soil fungi aid in digesting the organic matter in your soil why would you want to kill it?"

Because not all fungi are beneficial.

I don't know about using baby shampoo for this, but some people have reported that using corn meal at 10-20 lbs per 1000 sq ft will eliminate some lawn fungi (it works by promoting the good fungi, which eliminate the bad).

There is a product called "Plant Wash" that has been used to treat fungal diseases on top growth of plants. It is basically generic baby shampoo.

It is true that not all soil fungi are beneficial just as not all soil bacteria are beneficial, but since the vast majority of them are why kill off all of them to get the few that are not beneficial?

They're not talking about the soil fungi. They're talking about the fungi on the grass. They're trying to get rid of the bad stuff.

If you read what David wrote, the baby shampoo is used to treat the fungal diseases on the top growth of the plants, not to kill all the soil fungi.