tl;dr - Because of an expected cultural mismatch between East x West work practice.
Disclaimer: I am from a Western culture background, but I have worked in China for 2 years.
As mentioned by @SSimon the question is too broad, but I will drop my two cents. In principle I do not agree with the premise of career suicide in the broad sense, but I do see how graduating from some faraway, poorly-understood university may damage one's career.
I take the question from the standpoint of someone earning a PhD in the East seeking a job in the West. Originally the OP used the term "East" instead of Asia, which was culturally more appropriate, here. There is a large cultural gap between the "East" and "West" directly affecting on how professionals interact. Apart from a number of stigmas associated with distant cultures, one would expect frequent misunderstandings central to teaching practices (as per Academic jobs) and work relationships in general.
Taking a PhD in a radically different cultural background associates such cultural traits and perceived stigmas with an important line of your CV. I will that illustrate with key examples below.
(i) Western culture is strongly influenced by Greek philosophy and Christian principles. That results in that doubts and disputes are expected to be sorted out with logic and open dialogue. Also one is not morally accepted to seek usury, in the sense of short-term openly-declared advantages at the expense of one's partners. This mentality can be radically different in distant cultures. For instance, in Eastern cultures some unofficial hierarchy (e.g. age, status, caste) may dictate teaching/decisions overruling any objections, and even imply that a "leader" always expects advantageous deals. It is easy to foresee how that will quickly turn professional relationships awkward to an employee or manager coming from a different cultural background. For instance, anyone openly seeking advantages over the other part in negotiation will be perceived as a cheater in my country. Another simple example, I can say for sure that most of my colleagues would immediately refrain from hiring an Asian teacher, for fear of his/her methods.
(ii) Eastern cultures are strongly emphatic on a fashion "face culture" which is hard for Westerners to understand and accept. Again, this can quickly render a professional contact sour, as a westerner feels skating on thin ice without a map. Asking direct questions may offend like demanding explanations; the meaning of silence in a conversation is an emblematic example of communication mismatch. ...which bring us to the next main point.
(iii) Finally the language barrier is expected to be large. By language I mean both the idioms and the logic behind communication. Western languages are dominated by Latin eloquence and Germanic precision. One can fairly easily shift as a francophone to communicate ideas in English and still be understood clearly. Many Eastern languages emphasise on (face) interpersonal formalities and appraisal, on the need to communicate implied messages. These can be easily seen as undisguised flattery followed by "beating around the bush" which are behaviours frequently frowned upon at the work environment in the West.
The above list should embody associated issues, such as different methods and approaches to problems, mutually intrinsic behaviours perceived as arrogance, a mismatch regarding gender differences, etc. Therefore I believe an expectation of major cultural mismatch is the main obstacle to someone coming from , for instance, Asia seeking work in an American institution. As a closing remark, I emphasise I do not think a career suicide exists where one stays within the same cultural sphere where he obtained his PhD, as illustrated by the majority of employed residents having graduated at local universities, to be found anywhere. Also in such cases I believe the preference for local culture and standards are dictating the edge of locally-educated candidates.