>This is a fruiting chamber, not a mushroom growing device. Fruiting is by far the most trivial part of mushroom growing.

You've hit on exactly the value being provided here - they are handling the culture, inoculation, spawning, and colonization stages and selling you an expensive box to put the result in. Sometimes people just want a quick fun activity and they don't want to research it beforehand. This product fills that need - send them money, they send you a mushroom growing experience.