So what? Maybe FOSS cannot get us a competitive modern desktop, but in many areas open source projects have virtually eliminated all proprietary competition. Linux is running everywhere these days and e.g. in databases it is among the open source options where the growth is. Does FOSS need to be able to solve all software problems in the world for you to count it as successful?

Only if by everywhere you mean cloud centers, where the likes of Amazon, Google and Microsoft have their golden eggs not shared with the community.

If you are going to mention ChromeOS or Android, ChromeOS is hardly a blip outside US school system, and what kernel is being used on Android is irrelevant to user space, there is Fuschia on the horizon and Google has been replacing everything, with the Linux kernel being the last piece of GPL code standing.

Then if you mean embedded, plenty of IoT OS are MIT based and even Linux Foundation now has Zephyr as alternative to Linux, all operating systems where OEM can profit without giving anything back.

If you mean compilers, plenty of embedded OEMs are now happy LLVM users free of contributions, while reducing their development costs.