Although one would have to be very careful with the parameters. This could easily hurt people who are trying to have legit conversations with someone.
Indeed, the parameters would have to be carefully decided upon. Personally I think it should be used at all ranks, but that's just me as I think that the low level of discourse can come from any rank especially with account sales.
I like this idea, though I can think of a problem or two with it. While it's unlikely to happen, if the balance is incorrect it could begin to affect service owners who's posts aren't always long or high quality. These users don't tend to wear paid signatures, though could end up getting punished for it.
Also, then there's the argument of 'does the length of post equate to the quality?'. A user could create posts which are low in length and helpful, though they would still be 'punished'* for making such posts by the system.
*I put punished in quotes due to it not really being a punishment, more of a restriction. However, some users could see it as such and therefore stop doing said helpful posts.
Certainly something must be done about such posts however, it's obvious they are simply posting for the money and have no intention to help the conversation in any way.
They could start bundling their posts together, though I don't think it would affect them as badly as you think (unless they really have to reply to more than x people per z hours and they are extremely fast at doing so). And no, the length of the post does not always equate to the quality, but a post that is longer in length usually forms more of a valid argument than one made just to cramp posts in. And of course, low length posts would still be fine, the idea is that if you did make x amount of
less than y words for a little bit. You could still actually post.
i like this idea a lot better; disallowing users to make posts that are below a certain word count, i feel, would be a tad too limiting on their ability to type out their thoughts on whatever discussion may be taking place. instead, i feel that adjusting the time required between posts (360 seconds for newbies by default, decreases as activity is accrued) based on the word counts of a user's recent post history (not counting words included within quote brackets) might be an effective tool against spam. that value, if it were editable to an extent by moderators, could also effectively serve as a warning against people who are getting close to a ban as well.
I think your idea is good as well, that could definitely be used to stop posts with low levels of discourse.
There would also need to be some exceptions to ensure moderators who move posts and leave a "moved" post don't get punished.