Agreed. Halper was in contact with all three of the indicted person's and Carter Page was useful to a fashion so no reason to indict him.
My summary of this whole thing:
-Carter Page was a known commodity, not smart enough to actually infiltrate the campaign but extremely useful in that the Title 1 FISA warrant allowed them to capture signal intelligence two hops out for a year on virtually everyone in the campaign, transition and the administration (July 2016 to July 2017).
-Popadopolos was a nobody but someone they might be able to turn on Trump if he actually knew anything, which he didn't.
-Stefan Halper is the "source" but only useful early on when Brennan was busy putting together the "EC" for Comey and collecting bogus intel from the Russkies in Moscow March 2016. That information was combined with dirt from Blumenthal and company and the Dirty Dossier was largely written by Fusion GPS with the background material he had done in years prior and handed off to Steele to give the color of actual investigation. Strzok visited Halper in the UK July 2016 when they began the official FBI counterintelligence operation.
Well reasoned!