Setting off supernovas would require considerable travel. The closest giant star that might go supernova is Betelgeuse at 430 lightyears. To set off a series of these stars in rapid succession would require pan-galactic transport capability (unless it can be done by remote control). It would seem to be a waste of energy, if not time and resources. And it would be a one-shot deal too. Giant stars don't form overnight.

Imagining that there are beings out there that are vastly superior to ourselves is quasi-religious. While it might be true even, they may be as restricted in their abiities as we are by the laws of nature. It may not be possible, for example, to travel between stars. That would prevent civilizations from undue interference in each other affairs, such as blowing up stars or stip mining entire planets. It would be interesting if that restriction were somehow built into this universe -- and when I say that I mean we were only able to evolve in a universe where undue extraterrestrial interference was impossible. Evidence of intelligent aliens visiting earth might be the extinction of our type of life, and certainly the failure of homo sapiens to achieve dominance on our own planet. This might explain Fermi's Paradox but also raise questions as to what IS possible? Are there limits to discovery? Is it possible to build a telescope that can observe every minutia of a civilization a billion lightyears away, making it unnecessary to travel the distance to learn about them?

Another arguement is that interstellar travel IS possible, and we achieved dominance on our planet because the aliens haven't gotten to us yet. Everywhere else, only non-sentient life developed because of alien interference. So naturally WE would wonder why there is no evidence of ETI, meanwhile other planets are living with the reality of being conquered. Just because we don't see it here, doesn't mean it isn't happening somewhere else.

Still another arguement is that if the universe is structured to prevent interference, then what is the ultimate purpose of it all? Are there other possible structures to the universe? What underlying mechanism selected this one?

It was possible for life to evolve in this universe, but the universe pre-existed life. Did the Big Bang scramble all the physical constants randomly, or destabilize matter turning protons into electrons and photons into quarks at random? Has this been going on for a trillion-trillion years and just got it right in the last 14 billion? Is it temporary?

Is there a bigger picture? Or a deeper complexity? Can logic alone decipher it?