You are probably correct. The Japanese sentence was wrong. It has typo.
It should be:
需要によって、契機 or 変換点がもたらされた。
However, the middle part was rather long and the author mistakenly chose the last-part verb that had poor or wrong collocation with the first part.
If it was spoken, it would happen all the time because human's brains are not so good.
If it was written, it should have been proofread before you read it.
On second thought,
需要によって、～～～が～～～に向かう契機となった can be acceptable, if you interpret it as:
『朝鮮戦争での米軍の需要によって、終戦から不景気やインフレに悩んでいた日本経済が成長に向かう』（という歴史上の）契機となった。 Yet, this interpretation is still logically wrong, if we think about it carefully, you know?
Therefore, you are correct.
Yet, Japanese people may just let this kind of typo go because the meaning is obvious and there is no confusion.
The problem is whether "により” or "によって" canbe the subject-indicating particle for the verb 契機となった or not.
"日本経済が（主語） 契機となった（述部)" is definitely wrong because the meaning doesn't make sense or is changed in this context.
The subject of this context should be この特需 with no doubt.
Therefore, I thought and still think that により and によって should be typo for が or は in the orthodox and standard Japanese.
However, maybe they can be the subject-indicating particle in "broken" Japanese or something.