Sulphur in this state is pretty rare, or at least has very specific way of forming, and as far as anyone knows is a clear indication of volcanic activity. Much of why people study other planets is I hopes to learn more about our own. At the heart of it, science is about proving yourself wrong. All of the years of scrutiny and testing is about proving yourself wrong. That’s why junk science gets thrown around when someone has an idea, and gathers data to support it. That’s garbage.
But back to your original statement, yes most of the universe is made up of the same stuff. So that’s why it is interesting that you can look at Venus, Earth and Mars, which are all vastly different from eachother; and and use that to learn about why Earth is the only one currently successful even though they l started out similar.
As far as anyone knows finding these rocks further shows that mars probably had volcanic activity at some point. Volcanic activity is understood to be one of the necessary factors for life forming in Earth.
That spring boards into what else happened or didn’t happen on earth that didn’t or did happen on mars. Same can be done with Venus.