If your language has a pattern grammar where one subset of numeric literals is valid as a pattern and another isn't, your parser is simply broken. There's no question of prioritizing this or "real-world" use cases. It's a basic issue of does this work like any reasonable programmer would expect. The response there is nothing more than "you're holding it wrong"[0].
[0]:https://www.urbandictionary.com/define.php?term=You%27re%20H...
The question is not whether it’s broken or a bad experience. Clearly it is. But software engineers KS stuff like that all the time. The question is: is the cost-benefit worth spending extremely limited resources to address? It is not hateful or dismissive to ask that question.
1. do other languages allow this? i.e. have other languages prioritized this for development?
2. what are practical situations where it has come up?
Which seem like pretty straightforward questions to ask if you’re trying to prioritize this issue. I get that Evan was a bit curt in asking (2), but I don’t see an accusation of bad faith…