I've been following the field for awhile, so I'm aware of the barriers to success; it is, as the engineers like to say, a non-trivial problem. But I can't possibly be aware of every development, so it's really helpful to get your perspective.
I agree with the general consensus that we're a ways off from accurate machine transcription of group discussions, for the reasons discussed; that several conversations can be active at once, interference from other background noises, comprehending context, etc.
The point about late-deafened people being able to work with lower accuracy is a good one. I'm like that, I can recognize phonetic mistakes and mentally substitute the correct word because I know what it intended, but I have lot of born-deaf friends who would be lost.
One reader took upbrage at rusotto's joke about being able to hear doesn't help here. Me, I laughed. I know what it means to be bored silly even when everything is clear, and even ASL conversations can have the same problem. Another point about referring to deaf folks as "vulnerable" - yes, most people would resent that sort of label, even among those who understand it's not done with malice.
About communications with my mother - yes, we can converse by text, or through an ASL interpreter, and via video relay, and we've done all those things. But each of them is mediated to some degree, and working through Siri is too, but with an important difference; the other mediated techniques are more intrusive and divert focus from the person you're conversing with.
In video relay, I don't see my mother at all - I see an interpreter. Text - typing or writing - is also face to face, but it's slow. An ASL interpreter divides focus between the person I'm conversing with and the 'terp. All of these options work. The difference with Siri is, I can see her as she's speaking, focus on HER, read the text generated by Siri and match that with the facial expressions and body language.
One point made was the capacity for reading fast enough to keep up with transcription of a full table of rapid-fire conversation; I agree that would be tough.
Probably the most practical solution now is an ASL 'terp for those (like me) who know ASL. This is one area where the human capacity for a complex task trumps current tech.