A point that doesn't often get brought up in this discussion is that $0 software was virtually nonexistent at the time of the founding of the free software movement. In the internet's infancy, when software was still delivered on physical media, it made little sense to give software away for free because the shipping and material costs would drive the cost to the user significantly above $0.
Not that there wasn't ever software given away for free. There was source code published in magazines for the user to type in and compile for themselves, and there were friendly neighbors who would give you a program that they wrote for free. Even in the earliest years of the internet, people were sending their programs for free over the network.
But in a way, free-as-in-speech software predates free-as-in-beer software.
Actually, software was free at one point. Given without extra cost with the hardware. The concept of piracy wasn't an issue when the number of computers that could run the software ran in the two or three digits (maybe even four digits worth of computers). Also, without software already existing, those multi-million dollar computers wouldn't be worth the price.
This started changing when computers became plentiful enough to sell to a mass market. Bill Gates certainly saw the profit in selling only software (I'm not saying he was the first to do so, but I do suspect he was among the first to do so).
Not that there wasn't ever software given away for free. There was source code published in magazines for the user to type in and compile for themselves, and there were friendly neighbors who would give you a program that they wrote for free. Even in the earliest years of the internet, people were sending their programs for free over the network.
But in a way, free-as-in-speech software predates free-as-in-beer software.