I was talking about the MIT group (who explicitly discuss the differences between what they are doing and what Tesla considered), not the group in the article here. And you're right that Tesla also looked at non-radiative schemes for very short distances, e.g. Tesla coils, but at the time of Tesla most of the interest was in long-range power delivery (which never worked out because of the problems with radiative transfer, and in any case such schemes were supplanted by the wired electrical grid).

Tesla coils involve large electric fields between the source and receiver device, and so (a) are quite different from the magnetically-coupled resonators the MIT group proposes and (b) are impractical for the short-distance power-delivery applications considered here because they can dissipate too much energy into the environment.

The MIT group is not proposing to use omnidirectional (or directional) radiative energy transfer, which indeed would radiate most of the energy into the environment, and only a small fraction into the receiver, and even that could be eliminated if something (e.g. a person) walks between the source and receiver.

They are proposing non-radiative resonant energy transfer, in which both the source and receiver are resonant oscillators at a particular frequency coupled via the near field (non radiatively), and hence preferentially transfer energy compared to anything else that is not resonant (with a long lifetime) at the same frequency. Furthermore, they are using resonators that only couple through their magnetic fields (the electric fields are largely within capacitors inside the device), which further reduces absorption of energy by the environment (because most materials are non-magnetic, energy dissipation is largely via ohmic heating, i.e. by the electric fields). Because of this, almost all of the losses take the form of resistive heating in the devices themselves; only a miniscule fraction is dissipated in the surrounding environment (e.g. a person).

Of course, this being Slashdot, it's not surprising that most posters never RTFAed and post nonsense "it's just like an inductive transformer" (nope, those don't use resonance) or "it's just like an antenna" (nope, that is radiative transfer) or "Tesla looked at this a century ago" (nope, people like Tesla were concerned with power transfer over long distances, which necessitates radiative mechanisms and hence low efficiency).