Nothing, but they are the best at removing viruses.
haha
they can be used to remove viruses but...
A:) you need to know what you are doing, and
B:) it takes a large investment of time and effort to use it for that, as well as knowing what you are doing.
You can't just "learn how to use Sysinternals tools" (I better point out that I doubt you are going to be using contig or handle to remove viruses, it's mostly procexp's ability to suspend processes that comes in handy here) you are going to need to learn how to use them to remove viruses; the general method would be to first identify all the "bad" processes, suspend them ALL, then kill them all. After that, you delete their files. So we need several steps-
First, you need to know how to identify unwelcome processes. Do you truly think anybody can do this? Some people get shaky knees when people mention exe files. Most don't know the first thing about them, nor which ones are included with windows and which ones are part of drivers and software packages, it's silly to expect them to know how to identify malware processes, especially since they could easily piggyback on other processes like winlogon anyway, in which case they would also need to know how to use the dll view and be able to know which processes have loaded "bad" dlls so that they can be forced to unload said Dlls, and then you'll need to suspend that thread because chances are the virus simply inject a piece of code into the host process to reload the dll when it recieves it's DLL_DETACH message from windows via dllmain().
Meanwhile, you can avoid almost all of this hassle by simply running malwarebytes, or even better, use a background AV. Additionally, you assume that a PC's owner is the only person to use a machine. This is often not the case. Do you truly expect that people should learn how to use procexp and simply let their children/grandchildren roam free on the internet? using process explorer to remove a nasty infection can often take hours. Should they teach their kids/grandkids/grandparents how to use process explorer? Seems like a huge waste of everybody's time, all the grandparent wants to do is play some bejeweled and they're being lectured on how to identify malicious processes. I thought that was the freaking job of a AV program? It is.
