When Microwaves first came out they were huge but with a tiny cooking area and they were not affordable, and were mostly in business kitchens and a few restaurants. I would love a freeze dryer but the cheapest I have seen is $1600 and they only have 4 small trays.
If you’re backpacking, wouldn’t you have to carry the same amount/weight of water to re-hydrate it?
Sometimes you can find filterable/purificiable water when you’re in nature. If you can’t you should reconsider where your planning to go.
Not necessarily. Most backpacking is going to be down in areas close to fresh water sources and you’d be bringing a water filter.
Hiking/camping where you can’t easily find fresh water is quite risky.
No, you locate water, filter it, boil it, etc.
I imagine it depends on the type of food, as there’s probably some proteins you can freeze-dry that don’t have to be rehydrated to eat.