It was esentially as meaningfull as OPs reply.
Ofcourse, the point of "this app should run in a browser" is very valid. The reply, he can just code it himself is in my eyes a passive aggressive way of saying "no, i said your point is valid, but actually think it isn't and therefore ill ignore it anyway."
Its obvioulsy, that a well developed web app should be runable in a browser and the developers could have thought about it earlier. They know their project better than anyone, so the afford of understanding how this piece of software works for an outsider is way to high.
"Your app runs based on technologies that mean you could easily port it to windows. But it doesn't run on windows? Downvote!"
"Your app runs on windows, but it's built on technologies that allow it to run anywhere else; why does it only run on windows? Downvote!"
See the pattern? Saying "I don't like your entire contribution because it doesn't run on a given platform on which I think it COULD run" is counterproductive and at best pointless; at worst rude.
I'm sure you could have made the point more thoughtfully, in which case it would both have been clearer and not damaged HN in the process.
I quite like desktop programs still, but I expect everything to be stored locally and not to need an account. I had hoped for a KeePass style db file that I could sync on Dropbox or something, but the last thing I need is more accounts and my data on some randoms server that could be taken down when they get bored, or run out of money/motivation.