Who said they're not good for the lawn? I suppose if you want it perfectly uniform and spray chemicals at it - but what bollocks. A fungi that's specific to particular grasses maybe - but not mushrooms.
A quick google tells me this:
mushrooms and toadstools assist with the breakdown of organic matter in your lawn – making the soil richer and full of nutrients. The extensive root structure of mushrooms can also help the soil retain water
So if you remember who it was, argue with them for me :P
Really can’t remember where I heard it,
but I got same as you when I googled it. Apparently there are some type of fungi that can be problematic, but not those that live in my lawn 😉
And yeah, that could be said by those who care about having manicured lawns, but I like mine’s natural, like you ☺️💙
!LADY