So far, it looks like nobody is commenting on Dave Winer’s own work.

Everybody has been influenced by Engelbart, but nobody uses NLS. Merely the ideas went into all the computers that we use today. Engelbart was so frustrated because he had more great ideas, but they were difficult to develop and he couldn’t get funding.

Winer specifically mentions Userland Frontier. It was a useful tool, which I’m sure helped with the development of RSS, just as NeXT Project Builder helped with the development of WWW. The problem with the Engelbart comparison is that there are countless other development environments, many of them free and/or not in a dialect of C and/or available via git, while the Mother of All Demos was unique.

I think the open-sourcing of Frontier was too little, too late. Frontier is an impressive achievement, but I don’t see why it should be interesting to me.