This reminds me of what Jeff Atwood had to say about people over simplifying the nature of stack overflow (and by extension, claiming it to be over valued).
He eventually responded about the fact that the little details mattered. From auto searching for existing similar questions to little prompts on framing the question.
Similarly, Discourse is being built with principles in mind that go beyond a threaded discussion. It's attempting to answer the question of "can we use software to encourage a civilized discourse?". It's easy to ignore this, and look at it as bloated. But in that vein, Stack overflow is a bloated Yahoo answers or any other. And we all know it isn't. Essentially, it's more than just "a web-forum software". That distinction really matters.
Relevant links:
1: http://blog.codinghorror.com/this-is-all-your-app-is-a-colle... 2: http://blog.codinghorror.com/code-its-trivial/ 3: https://news.ycombinator.com/item?id=678501
After carpet bombing this thread with my own criticism, this was a good reminder of why that was probably stupid. Thanks :).
I'm not gonna rehash the full deal, everyone knows the "PHP is a fractal of bad design" article. Whether you think that's an exaggeration of the problem's impact or not, it's hard not to agree that PHP has a lot of features that are counterintuitive, encourage bad coding practices, and make modularity/expansibility of the codebase a real challenge. PHP is fine if you do it right, but it's really a challenge to ensure that a bunch of volunteers are doing it right, 100% of the time. It's not a coincidence that the people who are using mega-scale PHP codebases like Facebook aren't actually running PHP - they've gone through and cleaned up some of the awfulness and run a language based on PHP. Those are the design decisions that the actual PHP standards group isn't competent to make, because anyone who's sane has run for the hills.
Discourse is indeed extremely overengineered, but I don't think the urge to start over on a modern language that has better design features is wrong per se. If you had a web forum written on ANSI C or COBOL, wouldn't you say that at some point the costs of an inappropriate platform or a limited pool of engineering talent outweigh the cost of just rewriting it? You don't have Facebook-level resources to refactor the whole platform, you don't have billions of dollars of sales riding on your software. It's a comment forum. To throw your comment back - if it's just a simple app to display text on a page, why not fix the technical debt and put yourself on the right long-term track?