These tools are very common in non-nefarious ways for troubleshooting networking, and while vendors set up to serve this space solely as troubleshooting tools, I've also built my own that can sit on a network link and monitor for problems.

In my case it was for mobile wireless signaling traffic (all the coordination for creating a mobile internet connection, handing the connection off between towers, etc), and I'd credit it as one of the reasons you're mobile internet connection is so stable. When LTE first came out, myself and many others solved all sorts of bugs in the equipment and protocols by using or building these sorts of tools.