To clarify a bit, in meatspace, property lines are easily defined, and it’s easy to tell whether someone is on your property. In cyberspace, their virtual location doesn’t match their physical location, but pretty much everything between your modem and their modem is not your property; you’d be chasing them down, which by itself puts you in a dark grey area legally. The ISPs have pretty clear rules about using their network for illegal activities, and using their network for such counter-attacks is, at best, of questionable enough legality that they could (and likely would) cut off your internet just to cover their own ass.
Also, the use of proxies and spoofing makes hitting the wrong target likely enough that it’s less like shooting a home intruder and more like lobbing a grenade into the middle of a crowd where you thought you saw someone who looked like the intruder. Ponder the liability issues on that for a moment.
In cyberpunk, there are two types of people who use such IC; those who commit other, more major felonies anyways, and corporations that are more powerful than any government. Which are you? Are you a major multinational megacorporation, or a felon that already lives outside the law,constantly looking over their shoulder to avoid prison?