That argument may hold if you buy only one pair of loudspeakers and never intend to make an upgrade. But when reading the last couple of pages of this thread, people who are on their third or fourth pair of active speakers have obviously paid for their internal amplification every time they decided to upgrade their active speakers, while someone upgrading their passive speakers may use their existing amplifier for all of them. And besides that, internal amplification also seems to have a shorter lifespan, on average, than most external amplifiers.
This isn't me arguing for or against passive or active loudspeakers, as I don't really have a preference. I just want to point out what some people seem to miss when saying that money will be saved when not needing external amps and speaker wires, as those are hardly things you have to upgrade every time you decide to upgrade your passive loudspeakers.