I don't believe it has been proven to anyone's satisfaction that that is the only thing it leads to.

Given the amount of developers not able to write multi-threaded applications with shared memory I would say it is very well proven.

"Given the amount of developers unable to write a compiler, it is well-proven that compilers lead only to bugs."

Where can I find a bug free one?

I think the proper question under the formulation you provided is, "Where can I find one that does anything other than produce bugs," since you asserted that bugs are the only result. To which the answer is: any of them.

the argued keyword in your previous comment is "only".

Written using a multithreaded browser, that runs on a multithreaded OS.

So what? Are they bug free from deadlocks?

Nothing of this complexity is bug free, but the fact and the points is that some of the most reliable software everybody uses every day -- OS kernels, DBMS, etc. -- are not just multithreaded, but heavily multithreaded.