I would agree with you "Today"Loneliness cannot be cured by machines.
However, this is only a matter of time.
It would be like saying, going back many decades when the very 1st scratchy wax cylinder audio player was first invented, and someone saying that Mechanical audio playback cannot be enjoyable for anyone who appreciates music.
It just needed the tech to gradually improve to a point where, with the right equipment you can close your eyes, sit back and experience something as is you were sitting there listening to live musicians playing.
Machines can and hopefully will advance to the point where millions of lonely people can feel better/happier and have something to interact with. It may not look like a human, but humans are brilliant at getting over that hurdle.
Take people on this forum with a family and kids.
Over years their kids move far away, perhaps over time some of your kids pass away themselves.
You partner passes away.
Your neighbours don't want much to do with you.
You and not able to do the things you used to do, so end up in a chair/bed most of the day, watching TV as that's all you can do, and if you are lucky you may have a 10 minute visit each day from someone who brings food.
You give them a device they can talk to, interact with and makes them not feel alone in their final years.
That's a winning and amazing product when it happens.