Also, the central beam pulse was 190,000 terawatts - 10,000 times the total power output of our civilization! I wouldn't want to pay that electric bill.
Still, this kind of mega-engineering would be cheaper than the ticket price of high-speed interstellar travel. The authors say there might be a scaling effect, where super-civilizations build extraordinarily powerful transmitters. These aliens might have limitless armies of self-replicating machines that tirelessly construct vast antenna arrays orbiting a star and sucking up solar energy.
Another problem is that such civilizations are probably rare in the galaxy. And, at the same time we need to assume that they'd decide to stick with radio wavelengths as a viable communications channel for reaching any entities they would be interested in contacting.
Less ambitious or less advanced civilizations might try beacons too, but the beams would be weaker, though likely to be more numerous in the galaxy.