Following on from my question about what admins are doing with their warnings and bans, I am also seeing an increasing tendency in the forum-sphere for mods and admins to lock a topic when it contains opposing opinions or negativity/problems towards the site itself, citing such reasons as nasty or abusive (example). Often it's only robust discussion that I would expect to see around a friends dinner table, or brain storming meeting in a business environment, and thus the reason given looks more self serving than legitimate. Do you actively use thread locks as a proactive or reactive measure, where a warning or ban cannot be justified? Do you allow your mods (or yourself) to lock topics and stifle discussion/opinions because it opposes their own or that of a vocal minority/majority? Do you require them to give specific reasons (ie. posts) as examples of why it was closed. Or is a generic reason, with little justification, enough? Do users accept that these days?