Firstly:

I would say that limiting WIP in a kanban system can encourage swarming because team members have to help each other rather than pick up new work

And then:

The stages in a workflow are not people, or even roles.  Just stages.  So anyone can do them.
It just happens that people tend to specialise their roles to stages.
So kanban allows specialisation, but also encourages people to break out of their specialisation by limiting WIP.

For example, I might have an analysis stage, and Bob, a Business Analysis specialist.
If the kanban system has throttled analysis work, Bob could probably work with developers or testers to help them improve their productivity.
And vice versa.

Its this focus on workflow, while allowing for specialisation, that means that kanban is a suitable technique for teams of all agile maturity.  As teams learn to swarm, then their agility should improve as a result.