Nobody proposed this. What was suggested was a 1 BTC fee at sign-up and that's it.
Oh, Ok.
I don't think this would help.
There are always people that likes to hear themselves talking. (Don't know if this makes sense in english).
They would spend 1 BTC and than need to write a lot so that it's worthwhile.
IMHO better a very small fee per post.
With the small fee per post, I'd also like to have a button on replies to my own post, to pay of my asking fee to the writer of an answer.
Also, a possibility to pay a higher fee for a post that could than be donated to answers. Makes sense if I have a question and a good answer is worth some BTC for me.
The more I think about it, the more I like this Idea. Only say things that are worth the BTC. And if other think so to, your post will pay off itself.