This is about radiated power in any direction not exceeding what you would get with an omnidirectional 1W antenna.
So beamforming under these rules lets you use less input power for the same directional power. But it doesn't let you bundle all your power into a single direction.
Yes. Beamforming for the receiver, tho, is highly beneficial. MIMO does that for you. The previous poster is correct, the EIRP must not increase when antenna gain does; you have to turn down the wick on the TX.
So beamforming under these rules lets you use less input power for the same directional power. But it doesn't let you bundle all your power into a single direction.