It's not about the destination, it's about the journey.
This famous inspirational quote is at the core of an article which Benjamin Mako Hill wrote nearly seven years ago where he argued that to build a truly free world, we will not be well served, technically, pragmatically, or ethically, by compromising on freedom of the tools we use.
While Benjamin spoke about the freedom of the tools used to build free and open source software, the more general question, which I asked in May 2016 is:
Is it legitimate to use proprietary software to further free and open source software?
Almost a year later, my answer is still: Yes, if that is indeed the purpose. When we go on a journey to get somewhere in life, and in society, we sometimes need to travel on unwanted paths, and proprietary software is certainly an unwanted path.
The problem with this is you sometimes get very comfortable on this unwanted path, especially if it offers you something more than the road you would otherwise take. But there's a caveat.
L'enfer est plein de bonnes volontés ou désirs (hell is full of good wishes or desires) - Saint Bernard of Clairvaux
More commonly, we tend to say that the road to hell is paved with good intentions. Using proprietary software, when the aim is freedom, is certainly a good intention, but it has the risk of backfiring.
On the other hand, anything we do carries a risk. For most anything we do, we weigh the risk of doing something against the advantages it may give us. In some cases, the advantages are so small that any risk isn't worth taking. In other cases, the advantages are significant, and a certain amount of risk is warranted.
We would love to have definite answers to the ethical questions in life, but ultimately, all we can say is: it depends. Your perspective is different than mine, and history will judge us not based on what roads we take, but by the impact we have on society.
And as a community, we should definitely consider the consequence of our actions, we should prefer free and open source software whenever possible, but we should also be aware of the impact we have on society, and make sure the road we're on is actually making an impact.
If it's not, we may need to try a different road. Even one with proprietary parts. It would be a risk, but when you have weighed and eliminated the alternatives, whatever road remains, must be the right one. For you. At that point in time.