General

From my conversations with a number of feedees and gainers, I'd day maybe 65% don't want to be immobile for real. It's strictly fantasy. But, there's still a good chunk of people who actively want to become immobile but don't have the means or are actively working towards it.

Having been a caretaker in a non-fetish way, I feel that most feeders into immobility are woefully unprepared - especially if they plan to be the sole caretaker.

If a situation occurred in which a feedee could no longer complete everyday tasks and they were in a feedist relationship it would be on the feeder 100% to help the feedee.

from my experience as an encourager a lot of people fantasize about being immobile but the majority would not consider going there IRL .. it's just something they want for role play. I think many are turned on by the physical limitation of being that big (being stuck, being too big to fit in/through stuff, not being able to pick up something off the floor, etc..) but not the actual health risks associated with morbid obesity (there are exceptions of course).
As a feeder you do have the right to discuss limits with your feedee if you are in a committed relationship since you both will have to live the through the consequences of your decision. And I totally agree immobility could be a sexy fantasy for role play but in real life it would be a deal breaker for me.