Good for you for punching that man, uglyswan. You should totally feel entitled to defend yourself with all you've got when you feel in danger like that. It sounds terrifying, and you held your own, and got out of a tricky situation on your own wits and strength.
The point I was making upthread is that people really need to be individually singled out in order to snap out of bystander apathy. If you don't know their name, they can be singled out by the colour of their top, or an object they are holding. And then they need to be given a specific task, so that they can't use their cluelessness, too, as a justification for not doing anything: call 999, walk me to the next exit, hold this person's arms,...
This puts the onus on the victim, or on a more clued up bystander, to single people out and issue instructions. It's not fair, but human psychology being what it is, it's still a good tip to know.
In your case, although you called out for help, sadly, the people in the carriage probably were still able to feel unconcerned when you called out for "somebody", because everybody in the carriage is a somebody, and so nobody is personally responsible, and "help" was something they could still kid themselves was not within their ability. You were right to ask the people in the carriage, collectively, for help. They were totally wrong, each of them, not to intervene. This is on them, not on you.