>It is like growing food on industrial scale.

How many people do you think know how to do that today? It's in the millions (probably 10s to 100s), scattered all across the globe because we all need to eat. Not to mention all of the publications on the topic in many different languages. The only credible case for everyone forgetting how to farm is nuclear doomsday and at that point we'll all be dead anyway.

>If it breaks now with the knowledge gone and we have to learn it again it will end the civilization as we know it.

I don't think there is a single piece of technology that is so critical to civilization that everyone alive easily forgets how to do it and there is also zero documentation on how it works.

These vague doomsday scenarios around losing knowledge and crashing civilization just have zero plausibility to me.