[IMG] I disagree to a point. Charting reflects all of those...

I disagree to a point. Charting reflects all of those previous bag-holders who will be looking to get out at a certain price (which will provide resistance) as well as watchers waiting on the sidelines for the price to get to a level where their own valuations indicate the stock would be a good buy (providing support). Along with many in other situations.
In addition to this, the oscillating patterns do repeat (wedges, triangles, flags). Perhaps not every time but with stops in place you can limit the downside risk while setting up potential large rewards. As Mohnish Pabrai said "Head I win, Tails I don't lose much".
Even for long term investors (as opposed to traders), tracking momentum can help provide a good time to enter a stock that the market currently has in a downtrend. When it breaks that trend line could be much lower point than when you first found the company, saving you from that anguish and self-doubt of buying your parcel and watching it dump 10-20%.

Of course one would need to consider the fundamentals, trading while ignoring these is like picking up coins in front of a steamroller.