LINE did.
And it is also partially owned by Softbank.
Would that indiciate that Korean software companies are only able to penetrate one economy at a time?
That would be a very weird, but interesting thing to investigate.
So I am simply surprised. My knowledge must be incredibly out of date.
And I don't think it takes conspiracy theories to explain it, maybe users don't like platforms that isn't dominated by similar users of their primary language, or maybe there are something else that prevent app experiences optimized for two distinct cultures at the same time.
With some amusing exceptions: doctors are exclusively on WhatsApp; older (60+) people are often only on WhatsApp (and pre-Microsoft Skype before that).
Having traveled extensively in these places, I always theorized it was due to UX behavior aligning well with the local languages. While the countries WhatsApp dominates speak different languages, they all use the Latin alphabet. In Russia and APJC there are many non-Latin alphabets used and those languages may also use different directions for writing/reading than Romance and Germanic languages.