But why CX made these decisions?
Are the load factor on these routes so high that they don't care about OTA?
Btw, are there other airlines on OW that does this too?
Yes, their load factors are very high on those routes. In addition, there are people like me who have own preferences, e.g. request for specific booking classes and may wait for a few days before buying tickets

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For me flying non-stop SFO-HKG, CX is the only OW airline. (It is codeshared with AA.)