There is a reasonable, non-"culturist" answer to your question, which is that ASCII admits of a monospace typesetting in which each character is fully isolated in its own box and does not interact with any others across the box, nor are there any combining marks or any of the other vagueries of Unicode, and there's a very limited number of such characters. Possibly Hangul can claim that, I know Arabic and some other scripts can not. Other languages that can claim this include I believe all European languages (the accents are rare enough you can just represent them as characters of their own rather than combining marks) and Cyrillic. None of the ideographic languages can currently claim this, though I heard rumors that Japanese and Chinese are both experiencing some heavy pressure internally to go to an alphabetic subset of their language that actually would meet this criterion. (And not due to authoritative mandate, but rather the natural flow of language.)
It is a problem when you have languages with fundamentally different rules trying to share the screen, and that is also not a culturist observation; indeed one would think that denying this would be the culturist position.
While the precombined versions are much more common, Japanese does have combining characters to add voiced and semi-voiced marks to syllabic characters (e.g, か vs が, は vs. ぱ).
The ideographic languages can't claim "a limited number of characters". (7-bit) ASCII fits on a typewriter ball. (By "limited", I meant small, rather than merely finite.)
Of the various points I mentioned, in modern times this is probably the least important, now that RAM, ROM, and CPU are so dirt cheap. This wasn't always true.
