I don't know... They didn't say this was the limit of the power they had available, did they? Might be a modest power proof of concept. Actually with super accurate weapons like lasers targeting and target motion compensation is the hard part. It is one thing to have a "pretty good" idea of where something is, then shoot a smart weapon at it. This engagement sequence relies on the weapon for terminal guidance.
But with a directed energy weapon, the "launch" platform, no matter how far away or doing who knows what in terms of motion relative to the target is the final arbiter of hit/miss.
I think it is yet another step on the path to effective directed energy weapons.
Someone else a while back pointed out that if a solid state laser system could be made small enough... Well, take the STOL version of the F-35... Pull the vertical lift turbine out, and put a generator in there on the shaft from the engine. Quite possibly more than enough power for an escort directed energy fighter that could fly with a strike group and take out *all* the SAMs launched at the group.
no matter how far away or doing who knows what in terms of motion relative to the target is the final arbiter of hit/miss.