This isn't used as much today with modern large resolutions where we can get decent image quality from just rasterizing the font outline with anti aliasing.
This example, however, is using wasm embedded to ttf fonts which is not the same as ttf hinting byte code.
That sounds like an awful idea, too. I think a font file should describe the fonts form, but it should not describe how it is gonna be rendered. That should be up to the render engine of the device that is going to display the font (printer driver, monitor driver...). But I guess this idea is from a time when people were still using bitmap fonts.