I'm not sure I follow the criticism here. Is the issue that a paid product only supports Mac, or an open source project didn't build for multiple OSs?

If it's the first; I've seen tons of Mac only software due to the perception that it's a more lucrative platform. (Users are price tolerant for good products).

If it's the last; scratch your own itch. Since it's open source you can write the softer yourself. I'm not sure if this outlook is the diy zeitgeist I grew up in, or just being old. I'm curious if this is still a common belief.