While the PC-98 became the dominant PC architecture in Japan (up until Windows 95 made it irrelevant) I don't think it had any significant advantage beyond BIOS support for Japanese. On the other hand, it had the significant disadvantage of being largely proprietary to NEC.
IBM PC compatibles could made by anyone, including by a number of the Taiwanese companies that today dominate the PC OEM market. The lack of ideograph support on IBM PCs had a very simple solution: the Hercules Graphic Card. This card, introduced in 1982, was basically an MDA card with "high resolution" monochrome graphics support, the missing piece that prevented IBM PCs from displaying ideograph characters. In particular the card was designed to handle the Thai alphabet, which like Chinese ideographs can't be displayed properly on the MDA or CGA cards of the time.
The Hercules Graphics Card was soon cloned and quickly became a de facto part of the IBM PC compatible architecture. Given the availability of relatively cheap clone IBM PCs made in Asia and capable of displaying ideographs and other Asian texts, it's really not surprising that the proprietary NEC PC-98 computers didn't catch on there.