I see where you are coming from, although again, doesn't the reason for the agoraphobia have to be taken into account? For example there are many reasons for people to become agoraphobic. Mine personally is a spin off from having PTSD.
I saw a therapist in Belgium for appointments for 2 years paying privately, she had this same view of walking daily, pushing myself. I did push myself, walked daily for 2 years and never managed to get past the local shop in a small village due to terrible shaking. What made it worse was that on two occassions people stopped me in the street to ask if I was ok (this of course made me realise how severe my muscle twitches are and my shaking.
I kept going and didn't give up, yet one day at the therapists meeting she said "I really can't help you, you are not trying hard enough and to be honest I don't think I am experienced enough to help you with the amount of trauma you have suffered", she had no idea how hard I had struggled! It knocked me for 6.
Over 4000 euros spent which we could ill afford, I returned home devestated.
It was only when I saw a psychotherapist who's expertise was trauma that I felt someone could really relate to what I was going through.
I'm back to square one now, today the GP phoned since I am unable to sleep and she suggested I put lavender oil in my bath. Great idea, just shame that she has no clue about severe trauma.