I said most and NOT ALL (posts).
And yes it can be coincendence as batches of mobos being bad or worse than another batch are quite common occurences. In most cases mobos are made in several factories in different countries. You do get varying quality even among boards made in same batch for that matter. It all depends on the quality control level. And some manufacturers have higher than others on average.
The posts are useless in the sense that in most cases they are not reflective of worldwide experiences and you can only know if it is by thorough research. And thorough research would negate the usefulness of these posts no?