Conclusions

As we said before, other UNIX-like systems have a procfs. However, is in linux where it becomes powerful and very used. FreeBSD removed procfs from the system. They now collect system information by means of system calls directly. But if you want to run linux programs on FreeBSD, you need to install the procfs emulation package.

There are several applications and libraries that use procfs. Some of them are procps, libgtop or lkmonitor (I take part in the last one).

Although there are other ways to gather system information, procfs provides a simple way to achieve this goal. Everything in linux is a file (sockets, devices, pipes...), so I think procfs uses a good and consistent strategy to offer this information.