Or maybe we'll get into that comic-book thing of multiverses, where you can explode one Earth but there are hundreds of others that are just fine.
That's also incredibly lazy.
But the fact is, how else do A-listers like Spiderman and Black Panther continue to make money for Marvel? (It's no secret they're getting sequels, as are the Guardians of the Galaxy with or without Gamora. I'm guessing without. My sense is that she and Loki are really-really dead, not just comic book dead.)
Nine times out of ten time-travel scenarios make for truly awful sci-fi, across all media. They're impossible to do well because they're basically cheap -- they take away any sense of serious consequence. They make things which should really matter into things which don't.