The idea of "necessary" is a bit of a slippery slope, although I admit it can go both ways. You have your idea of it, someone else might find that me living at home and having someone bring my groceries is what is sufficient. For me it is quite necessary that there is an accessible toilet at my office. Being a consultant who often needs to deal with clients at their premises, general accessibility is a great thing to have.
I sometimes even need to go shopping for toys, and I do even have hobbies. Whether my purchasing power is sufficient to encourage access on a purely individual business basis, is questionable in particular if my achievement of said purchasing power would be strongly limited by lack of access in ... uh, necessities.
Interestingly, I'm quite pro-market in most things and really like seeing it when a market is created to cater to in particular special needs, but when the market fails to provide for some people's general participation in the world at large, I see no problems in democracy making decisions that mandate "mindless commerce" especially in cases where competitive pressures would discourage individual actors from stuff like providing access, which in the long term and in aggregate is beneficial in the total costs incurred sense. Environmental protection is another case in point.
It's funny how I am probably the most understanding of the "you can't fix everything at once by legislating" kind of thinking of all the disabled people I know, but the sentiments expressed here that it's perfectly OK for me to ask for people to carry me around is what make me want to take a hard turn to the left...