I'll answer the second part first
what makes it so necessary to search for someone who has cured with "EXACTLY" the same symptoms as we have. I understand this is totally irrational, but how do we halt the continuous search that we hope will give us some "comfort"?
Remember we're dealing with a highly evolved distraction. For it to work it has to distract us and we all know how from an evolutionary standpoint picking low hanging fruit, taking out the weakest of the pack is a good survival strategy. The easiest way for this distraction to stay working is to isolate you. Keeping you in fear and DOUBT means it will stay in place for good. Instead of working to banish it you will spin in circles with your toe nailed to the ground going 'well ...but, but..but.' and never get started , but ceaselessly search for that person with 'exactly' the same symptoms (which are subjective anyways)
The easiest way for it to do this is to demand EXACT replication of the 'experiment'..e.g. turn a NON -test lab entity into a test-lab approved 'hard science'. The funny thing about that is that 'hard' science "isn't", but that's another discussion.
Given most of us still struggling have had symptoms for a long time and we believe in the concept of TMS, why and what makes us fear the symptoms so much
Conditioning. We have always expected the worst and Gotten it and now we intellectually understand Sarno's work BUT it's one piece of pliable new information against years of ossified conditioning. The Unconscious is usually lumbering several weeks behind the the conscious and that's why it takes at least a few weeks .... Once you engage and stop doing the 'searching' from your first question , most people begin to get respite within a few weeks...
I always describe TMS to people as 'OCD of the Body'.
When I was young I suffered horribly from OCD and did not understand what was going on. I thought I was Crazy, dirty and Going to Hell in a hand basket. It wasn't until I worked with a therapist Post-TMS healing that I began to make the connection. Sarno mentions it in every book, but having had OCD I can assure you they are Exactly the same. An obsession with a piece of information and minutiae that keeps one distracted and in agony...and even if resolved simply moves along to the Next thing to obsess about. Neither one has anything to do with Reality and is there to keep me away from what is really bugging me...and Both of them are there as protection mechanisms. Sort of like a mental cancer...always getting slightly worse...unless you can rip it out whole hog. You are never going to 'win' by reasoning with it.
I have worked with several people with TMS and that checking and re-checking is not unique but rather a part of it. Sometimes when I see no progress I realize that the person has tricked me into talking about their symptoms over and over and it usually begins with "Yeah.... But do you think? But.... But... But"
They Not only have TMS but also Entry level OCD. Both of them there to 'protect them'... until their life is ruined. That's why I always Kick against this crap... I am not subtle.... F-K Tms... Beat it, run ,scream,get free... do NOT let it be in charge. Treat that 'need to know someone with the exact symptom' as a symptom itself... whenever you hear it in your head tell it to F-K off. over and over...that is the same therapy I used to beat OCD and I have a pain free wonderful life now and have for 20 years.