Why even go through that trouble? In what circumstance would you need an `otf` when a `ttf` won't suffice? (Genuinely curious, I've wondered this for a while because I've never seen something that supports `otf` but not `ttf`).

TrueType fonts of that era typically came in separate Windows and Macintosh versions due to implementation differences. One difference was how Windows relied on an additional `OS/2` (lol) table in the TrueType font data, unused by Mac OS: https://typedrawers.com/discussion/501/can-someone-explain-t...

The arguably bigger reason is that Mac OS didn't support "data fork TrueType fonts" (what most people probably think of when they think "TTF file") until Mac OS 8.5 (1998). Before then, TrueType and other fonts on the Macintosh were resource-fork-only, because "installing" a font prior to 1992 meant using a special Font Mover utility which actually grafted the font's resource data into the Macintosh System suitcase itself at an unused Resource ID#. Attempting to even copy such a font to a Windows system would yield a 0-byte file on the receiving end unless one knew what they were doing. System 7.1 (1992) added a dynamic "Fonts" folder in the System Folder but still expected to see them as Macintosh resources.

An Apple-commissioned font like Chicago probably never had an official data-fork-plus-OS/2-table "Windows Version" made of them at all. Since the actual Bézier curve data (`glyf` table) was the same on either platform, it was possible to homebrew a Windows version of a Macintosh font or Macintosh version of a Windows font.

Upvoted for implausibly specific domain knowledge.

At one point I recall TTF hinting being patent-encumbered, but you bring up a great point — any patents surely have expired by now.