The underlying idea behind DCA is that by investing a fixed amount every month, you'll naturally buy less shares when the market is overheating and more shares

The underlying idea behind DCA is that by investing a fixed amount every month, you'll naturally buy less shares when the market is overheating and more shares when it's undervalued. Contrast this with trying to time the market so that you're buying up shares during a down market. The author substituted in "buy immediately" for "time the market." I'd say that the strategy you're referring to is the same as "buy immediately (whenever you can afford it)," but interpreted in a DCA light. You're right that it matters if we're talking about whether or not you have an existing savings you want to invest. But I don't see that distinction to matter here, since many people believe DCA is powerful because it rejects the idea of market timing and reduces risk, not because they're trying to put their money to work as fast as possible.