why do people think the LINN LP 12 is so superior to the Thorens (say 165 super)

I don't think LINN people are snobs, but I think they are very passionate about their TTs and are convinced that what they own is the better of the two.

AR invented the 3 point suspension + belt system, Thorens ran with it, then LINN saw it and made their own tweeks in scotland. 

I happen to own a Thorens 160td that I picked up for $50 which freed up some $$ to play with it, A little dampening here, a thicker bottom plate there, Cone feet, Sumuko pearl stylus. To me, it sounds great. 

When my LINN-owning friends visit, they make comments like "when are you going to step up and buy a LINN?"

Now maybe they are just joking around, like the chevy owner razzing the ford owner, but I don't think so. I think they really believe LINN is superior. 

Why not? If they own it , MUST be the greatest.
It is nonsense.  Don't listen to these friends.
who says the LP12 is better?  Certainly not I.
Why don't you do a shoot out and settle it? You may find that they sound different with some preferring the Thorens and some the Linn.
Thoren, TD145-166 a lot were made or the 121 or 124 are all better. Tons of parts too.. I sure like the way the 121 and 124 look in a heavy plinth. SQ.. very special with a 9 or 12" arm and quiet.. 

You can't tell what I like can ya? :-)

The Linn is not superior in any way. I have owned two of them. There was a time when it was the best turntable you could buy. It developed a following and the mythology blossomed around it. None of it is deserved. All it is is an upgrade AR XA. Ed Villchur should get all the credit for the design.  It is old hat in a big way. The "upgrades" are beyond silly but, Linn made a pile off the LP12 and jumpstarted an entire company off it. Good for them. 
The Thorens is just as good and a much better value. 
Perhaps your friends are suggesting that you listen to a well spec’ed Linn from recent times ( NOT 30-40 years old, which is what the naysayers are referring to, and the last time that they MAYBE listened to, or owned, the LP12!) and decide for yourself.
I have a contemporary Linn LP12 with a Koetsu Rosewood Signature replacing my VPI Aries / Van den Hull Frog and it is a tremendous turntable. Any piece of equipment that has been upgraded for many decades is going to get comments about earlier versions. It is a very fine turntable.
We had a Thorens 160 with a Grace 707. It was very nice. The LP12 with Ittok combo was better. But not by much. That was over 30 years ago.
My guess is better made and heavier platter by Linn. I also
owned Thorens 160 ''pro'' but prefer Linn. 
@nandric Indeed. The main bearing and the Jelco jeweled-bearing Ittok and the Valhalla board also contributed.
Maybe yes maybe no.
If it is such a great turntable why all the continual upgrades? The Linn is an overpriced cheesy piece of very old technology. It has been done way better since 1980. We old audiophiles who were the initial Linn buyers moved on to Sota and then Basis and SME, designs that are from every angle superior. We got rid of the Linns creating a huge used market. Now you could get one cheap and hype the mythology even more, just like old idler drives. The Linn is a better turntable than those old idler drives as long as it is placed on a rock solid situation and treated gingerly but it will never compete with turntables from the above three manufacturers. 
In a blinded test with the same cartridge in both turntables none of you would be able to tell the difference between the Thorens and the Linn, none of you. You can buy the Thorens for much less and then you don't have to spend a fortune buying upgrades. It does not need any.
If you want to work on something mechanical buy an old 911. They are a lot more fun than an LP12. 
If it is such a great turntable why all the continual upgrades?
The same could be said of your 911 !
@noromance   LOL! +1...
Folks, mijostyn knows more about Linn LP12's than anyone on this forum. Particularly since he last owned one back in the 80's...if then!
linn is musical, quiet and well behaved. more less lifely side.. think Roger speaker.

thorens is even more spice, musical and grunt. less neat sounding..

acquired taste really. 
If you really want to piss off your LP12 friends get a Heybrook TT2 with aluminum sub-chassis.
That will shut them up once and for all.
The Linn's heavier platter gives it better speed stability/more inertia. I have a LP12 and a TD160. Both can sound fine!