Observations aren't evidence at all. Evidence is things like statistics and video. Opinions supported by these objective facts are absolutely worth more than opinions unsupported by anything other than subjective observation. You don't need to feel inadequate if you can't be bothered backing up your opinions. Sometimes I can't either. There's no need to constantly attack others who do. It just makes you look petty.
As for your criticism of 'selective' evidence, you are again showing your ignorance. There is no evidence that isn't selective. Evidence is by its nature selective:
"Evidence is factual information used to support a claim or belief. It is information and research
selected from the best available sources to support a decision."
Evidence is used to inform decision making to achieve the most effective outcomes.
evidenceportal.dcj.nsw.gov.au