We use ours for all of those things, plus to keep other stuff dry like cement, to fill with heavy smallholding rubbish for the bin, sending skins off for tanning, lying on under the Land Rovers or tractor to keep a bit dry when repairing breakdowns in inevitably wet weather, covering wet concrete when it rains on it, storing noxious weeds in so they rot and can go on the compost heap, giving to friends for their heavy garden rubbish and all the other uses they have for them. There are never enough to try to find a recycling place, although there are sometimes gluts. We have to clear all the old insulation and rubble from having the roof replaced from the attic - not looking forward to that, but we'll go through every feed sack we have.
It's like empty licky buckets - how would we ever manage without them
Burning feed sacks, however secretively, gives off dioxins which are some of the most toxic chemicals to animals, including the human kind, and the environment. Think lambs with two heads or extra legs, people with cancers, land polluted. Please don't.