Working on the back-end side, there are still edge cases where ARM just doesn't work. You'll be using some container image and there's no ARM build. So you build it yourself and the build fails. After two days of poking and prodding it turns out the image is based on some wonky base image that has a libc that has never been ported to ARM. Re-creating the image on a different base turns out to be a big project. I've run into 2-3 similar but different issues like this in the past couple of years.