I guess it depends on the situation. There are quite a few people on here including myself who have horses that have been rescued. All 3 of my horses were in just awful condition when I got them but they have come a long way in the time I've had them. Still not 100% but nearly
Some have tbs, once again like myself, that are terribly hard to keep good weight on. They are a slender breed to start with and the tiniest amount of weight lost really shows.
As far all the others *sighs* I just don't know. Lack of education and a lot of people seem to have not been educated properly with regards to feeding.
And then there are those that can't afford to feed because of the droughts that are going on everywhere but they wont sell their horse to someone who will be able to care for it.
I've thought about this a lot myself and that's the best I can come up with :)