Well this is why those settings are adjustable. I would imagine the sites in question the site’s primary language is not Chinese.
This setting minimum is designed to help not have very vague topic titles. While it is very true chinese and other languages that use picto glyphs do indeed have a much more complete statement in a single glyph than say other languages like english and ones that use a 26 alphabet system.
So naturally system installed defaults will typically follow standards like 15 characters in Title and 20 character minimum for post requirements.