I agree to ur point that posts having large numbers of objections are auto archived... But I too have gone thru some posts that are too old (1- 2 yrs or even older) also archived even if they don't have any single objection rating..
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For example - 2-3 months back I was going through a post of Mr. Suraj Prakash (one of the monitors) which was more than 1 year old and I wanted to comment on it but I couldn't as it was archived... The post had not received any single...
more... objection but was still archived..
That makes me think that it's not like only controversial/abusive posts get archived here.... But this is true that abusive/controversial posts get auto-archived very soon if they receive sufficient objections...