I always thought that the intent was to underline the notion that the rank-and-file witnesses were NOT in the New Covenant; merely hoping to benefit by proxy h:
Wt hides the difference between the Kingdom and New Covenant. The new covenant is for forgetting/ forgiveness of sins, and it was even symbolised by the drinking of wine before there ever was a validation for the heavenly kingdom covenant at the anointing of the 120.
You are absolutely right "underline the notion". There is always a big chasm in the talks with the unexplained jump from the anointed kingdom heir partakers to the fact that the New covenant is with all, not just the kingly/priestly*** class.
A class act of wt obfuscation.
*** In the model, the not so "new" Mosaic Covenant, the law covenant was with all, but there were separate covenants with the Judaic kings, and the Levitic priests. there was different covenants in the " type" too, the Old/New covenants were with all. drink, all of you.