The great part is that unlike SVGs you don't need to include specific image files for each one, or worry about updating those files across lots of systems. Just update the font. Client wants to use their icons in their printed pieces? Just give them that font rather than a whole bunch of files. Include the font with articles for print, and the printer can outline all the graphics.

Tl;dr, fonts are just a fantastic way to bundle lots of vector files on a per-client basis. Plus most clients feel super special and cool that they have their own font!

And the tech we use is old. Old. We maintain these in FontForge, which is a Mac X11 app.