Some people have maintained that private ownership of the means of production ultimately destroys any society that sanctions it.
Conclusion (implied)
Private ownership of the means of production is not going to ultimately destroy a technological society, if it sanctions it.
Intermediate Conclusion
If the means of production become public property, that will actually endanger the survival of a technologically advanced society.
Evidence (Since)
Only private ownership of the means of production permits individuals to test new technologies without the majority's consent.
Evaluate
Whenever we read Role or Main Conclusion arguments, we prime our brains with a reminder that the conclusion will usually be the First Sentence or a Rebuttal.
This paragraph begins with an attribution: "Some people have maintained". We would anticipate that the author will disagree, starting with some pivot word like But, Yet, However.
Instead, the author initially concedes a point: "This may be true [in some cases]". And then she hits us with the Rebuttal Pivot: "But ... since [premise], [conclusion]."
We could say that the final claim is the main conclusion, but because of the rebuttal structure it feels fair to say that there is an implied conclusion that is disputing the accuracy of the attributed claim in the first sentence.
Goal
We're being asked about the first claim, which plays an Opposing role, as the entire argument exists to partially rebut this claim.
The author concedes that the claim may be partially true when it comes to less advanced societies, but she's implicitly arguing that it's not true when it comes to technologically advanced societies.