They are a "workaround" with long history: Windows 95 shipped Marlett for exactly this purpose of using fonts as well-supported vector graphics formats.
Oh, absolutely. It’s just a dealbreaker for me personally that fonts are monochromatic, single-layer, and difficult to position in web pages with precision and consistency. If those aren’t concerns, then icon fonts are a perfectly useful tool.
They are a "workaround" with long history: Windows 95 shipped Marlett for exactly this purpose of using fonts as well-supported vector graphics formats.