Peer review is important for checking the correctness of the results, among other things. It's not uncommon to find big errors; small mistakes are everywhere.

Peer review is of utmost importance. Any researcher can make mistakes. I can read papers and apply them, but I need expert opinion to trust the papers. I am not skilled enough in any but my specialties.

I do see papers with outlandish claims and very weak support. This kind of excessively bold statement I see in many papers is a red flag for me.

Its easier to tear down than build up. Resilient structures are tested structures and last the longest.