Re: the whole message
"why is MSE even searching for Stoned when it is ineffective on systems these days?"
For a few reasons:
* because, as someone pointed out above, it's cheap to add more signatures (things are much better than O(n) complexity we had in the very early days). If you can scan for it, and it's cheap to do so, then why not?
* because it's one of those viruses that your scanner is expected to pick up (and virus scanner manufacturers used to use number of viruses detected as a marketing tool)
* there are such things as virus droppers that will install all sorts of malware. The blockchain (or any random data file) mightn't be (isn't) a virus in itself, but if it contains the virus (which it doesn't) a dropper can pull it out and use it to infect something (so if I had an SQL database with lots of virus code, it would be nice if the av software could detect it in the db file)
* who says that it's ineffective? Some people still use floppies. (true, its not much of a risk, but the infection mechanism still works)
* by catching the floppy-only variant, you might also catch derived versions (like NoInt) that can infect hard disk boot sectors
Mostly, though, it's probably just a combination of inertia and anti-virus writers liking to keep old signatures around for historical/completist reasons. Maybe they should drop these old signatures, but imagine the embarrassment should one of these apparently "extinct" viruses have a high-profile outbreak and MS's program failed to detect it?