—The preceding unsigned comment was added by  (talk • contribs) .
I placed the Main templates in that article for two reasons: 1) to provide readers with a clearly-recognizable link to related articles of relevance, and 2) as a subtle encouragement for editors to rectify the current situation, where, as you noted, the "main" articles are not as long as the sections in the Battle of the Beams article.  I'm not confident enough in my knowledge of either radio navigation systems or of WWII UK military history to pare down the sections, merge into the narrower articles, and  write an elegant summary for each of the sections myself.
If nothing else, I succeeded in having at least one person notice the situation you mentioned... –  (talk | edits)