OK, use cases… Anything with more than trivial texts. NPC interactions, in-game reference, logs etc.
For example, if you want to have NPC selling things, having a table with price column, how they look column and stats column, and scrollable if too long would be very handy. In Visual Novels you will need a long scrollable talk log. Many concepts are better expressed with icons, instead of texts. such as “I’ll give you [carrot.jpg]x3 for [gold.jpg]x10”. Or “This gun is best against [zombiehead.jpg]”. Links will allow making cross-references and tooltips. For example, “Kill [meanine.jpg|ref = meanie43] near [planet.jpg|ref = planet128]”, with tooltip showing mini-map where this planet is, and click on planet link sets your autopilot there.