Fundamentally open source companies and no-revenue model companies are very different, I think it's a mistake to lump them together. The defining trait of a no-revenue company is the investors' confidence that massive revenues or at least a bombastic acquisition will come further down the line.

This model does not work for open source companies, because the "figuring out how to make money later" step typically can't happen without a massive pivot (whether it's all that likely to happen with your typical no-revenue company either is open to debate).

Maybe the break-even point in open source companies tends to come at a later point, but the path to revenue needs to be baked in from the start. Typically, switching on a revenue generator later will require more than just putting some ads up on the company site, so if massive changes are required to make that happen you must include those plans in your DNA from the start.

Open source and zero-revenue companies share the assumption that reach and influence can be translated into money, but when running an open source company the nature of that reach has to be designed more carefully.

The obvious answer would be that you are not trying to raise money, but you are building a one-off "work of art" that will sell for million dollars.

That gives an idea of why such a a zero-revenue business model makes some sense, but also gives an idea of why it's incredibly hard to make it work.