I assume you don't believe in radiation either?
There's a difference between light and encoded information transported via light. One is pure energy, and the other is information via a medium.
Also, thing is, it IS related to the Evil Energy. That's where Wily got the idea for an airborne computer virus in the first place, and he used the Evil Energy and studied it enough to know how it works, and therefore made his own, and test drove it with the Roboenza he spread from his space tower that nobody saw him build.
I haven't got a huge problem with this premise, actually. Problem is we're finding out about this now, after all's been said and done so far with Mega Man X and Mega Man Zero, particularly.
Then, at some point, he built Zero, sealed him away, and went back to it, refined it, improved it, and sealed it in Zero's capsule. it leaked from there and yadda yadda we know the drill.
Which brings us back to my previous questions: why?
It IS an airborne energy. if you can accept the Evil/Alien energy from 8, you have to accept the Sigma Virus as energy in the X series, since they are related. And I mean come on, it a [tornado fang]ing science fiction videogame series. Are you REALLY going to say, "NOPE, THIS CAN NOT EXIST IN A FANTASY SCI-FI SERIES ABOUT RIDICULOUSLY HUMANLIKE ROBOTS WITH ROBOT DNA AND OTHER IMPROBABLE THINGS DO."
It's a invocation of magic. Calling something "evil energy" or calling a virus an "energy body" is barely different from invoking the influence of mysterious, evil spirits, which shows little to no understanding about what it actually is or how it works. This is more befitting of a fantasy
setting--where the improbable is common and without much explanation--but not of a science fiction
setting, which is based on what is probable. I don't think the Sigma Virus or Evil Energy as we know it has enough basis to pass muster as a good sci-fi concept. It's just obfuscating technology we're already familiar with or take for granted. It gets my goat because it's not even interesting. It's just "BOOM. There's a virus. It makes people go crazy, except for the heroes or whatever. Only fairies can kill it."
The reason I wouldn't take it that seriously in a setting like Mega Man is because Mega Man never took it's plot as seriously as Mega Man X did (with the welcome exception of the American MM7). Mega Man feels more like fantasy where Mega Man X feels more like a legitimate sci-fi story, which is why I want MMX to be expressed more like Blade Runner or Ghost in the Shell.