> The MSLU was announced in March 2001, and was first made available as a compatibility layer for Unicode-supporting code written for the then-new Windows XP RC1 in the July 2001 edition of Microsoft's Platform SDK.

People had to deal with local language file names since Windows 3.1 at least and it became very common with Windows 95. Good luck if you wanted to deal with files named in more than 1 non-ASCII language (very common in Europe or the Middle East).