One possibility is that designers can show their work even if it isn't open source. If you did the design for a public-facing website, you can show it, talk ab

One possibility is that designers can show their work even if it isn't open source. If you did the design for a public-facing website, you can show it, talk about it, make it part of your portfolio. A lot of the code is viewable in the browser anyway. Backend coding on closed-source projects, on the other hand, is rarely visible, rarely credited, and under some circumstances, you can get into hot water legally by sharing that work. So open source may provide a degree of professional exposure for coders that designers already get regardless of whether the project is os.