I ranted about this in the unofficial Alexa Slack team and the people there gave some plausible (but unsatisfying) reasons why it works like that. I'm not a huge fan of Amazon though, so I'm happy to blame them. Essentially it boils down to different regions being treated as different "languages" as well as having features rolled out to them at different rates.
Google's speech recognition is supposed to be much better, though not sure if they'd allow "one intent to rule them all" like you want.
For free-form speech recognition in Alexa, the best option I've seen mentioned on the public Alexa Slack team is using the "SearchQuery" slot. So you'd still have to make a weird catch-all intent that would eat up some of the words (and you wouldn't be able to see them). At the same time, you shouldn't assume that Alexa will give you very good results with such loose constraints. Even in my simple skill it's very bad about confusing certain pairs of words.
Sometimes I wish it didn't. They don't give you the original audio, any kind of confidence score, or even alternative hypotheses. It's really a pretty rigid platform. A lot of things that seem like they should be reasonable are impossible. Eg., I'd prefer to just say a list of post titles and let people interrupt Alexa when they hear something they like. That is impossible right now without pretty serious hacks.
Yeah.. turns out that's actually a friend of a friend. I'm curious to see what people prefer for obvious reasons :). The advantages of my approach are personalization, interactivity, and scalability beyond just HN. Theirs is probably going to be a nicer experience than I can do for non-interactive use.
Alexa does most of the hard stuff: speech recognition / intent detection, and speech synthesis.
My back end is a simple Python service on GCP that handles HTTP requests from Alexa. The same service also downloads the HN front page from the FireBase mirror and gets summaries from this API:
It's not perfect though, so I may switch to a more expensive summarization API, supplement it with manual summaries, and/or train my own summarization model.