There's nothing new here, a company can have a crap tech stack and still build a successful product if it has a competent team and good leadership.
This was I imagine a bit of a PR problem for FogCreek, because at the end of the day they were using Visual Basic to build a Windows-only website, not exactly the most awesome stack in today's world (or yesterday's for that matter).
It's normal that they want to communicate to the world the fact that you won't have to learn their custom version of Visual Basic in order to work there. It's also normal that people aren't giving them a pass that easily.
People seem to be mistaking the big story about Wasabi today. Wasabi worked. Yes, they're migrating away from it --- ten years after introducing it. They defered to 2015 what people on HN are telling them they should have done in 2005.
Not only that, but the "port" to C# was mechanical. They didn't rewrite to get away from Wasabi. Because they put the time in to build Wasabi, all their code was instrumented, and they were able to write a program to do the final port. They deferred the port for a decade, and also mechanized it.
I can't help but think you've taken exactly the opposite message away from the posts today that the authors intended.