The sole mention of directed energy:
> Directed energy has been proposed as a cost-effective alternative, but introduces its own scheduling constraints — dwell time, platform coverage, atmospheric degradation — with similar scaling issues
The author is doing the thing where a writer tries to bamboozle the reader into a conclusion without having to prove it by overwhelming the reader with nouns. Life is too short for shitty gosh gallops.
Bearing in mind the three constraints quoted, which of these do you think a country's deployed directed-energy weapons (e.g., US, Israel, Russia) would be useful against:
You are basically complaining that the article is not about a your preferred, different topic.
Directed energy defense does not really compete with a system like GMD at all, because the range is extremely limited by comparison.
The US might be able to justify throwing a few billion at a few dozens of ICBM interceptors stationed in a handful of sites, but protecting every potential target (city, military base) with some kind of laser array is obviously unrealistic.