Not always. More often the purpose of a chart seems to be to:
- Make the presenter look smart, or at least cool.
- Make the presenter’s product look better than the competition, despite the facts.
- Accentuate (fabricate) the positive and obfuscate the negative.
- Hide the fact that the presenter doesn’t know what’s going on.
Raymond backs up his assertion with a counter-example which I presume looks like this, with barely distinguishable green gradients and a useless legend.: