Are we already capable of going to Mars this very instant but just unwilling?

[Chronos]

@Stranger_On_A_Train

The third is that unlike having two counterrotating rings, a mass-tether system means having to propulsively induce rotational momentum into the system to ‘spin up’, and then propulsive remove the momentum to ‘spin down’ when you need to maneuver the individual components, which requires a large amount of additional propellant mass.

You can do it with an arbitrarily small propellant mass. Just extend the tether further beyond the capsules, and put the spin-up rockets at the end of the tethers.