1. Market action discounts everything.
There is two enterpretations of this statement: weak and strong. The strong one means "each news causes instant and precise change in prices". That is, the effective market hypotesis. Were it true, the charts would look like staircases, without trends and oscillations. So, it is obviously wrong.
The weak interpretation of this statement is "non-effective market". That is if, say, China bans bitcoins
, the prices would fell, but they would fell too much or not enough. Market will react, but with some error. Since the statement doesn't tell us the size or even sign of this error (too much or not enough), it is as useful as it's opposite: "market doesn't discount everything". Which we can observe right now: stream of "everything" is coming, but market does seem to ignore it.
tl;dr; Depending on interpretation, the statement "market discounts everything" is either false or useless.
[/trolling] OK. It's useful, but it's not that easy to use as it may seem.