In Risen and Haunted, there were ways to focus your farm for red border weapons. You could get 1 red border of your choice per week once you unlocked the ability through the war table. While it took a time investment, you at least were guaranteed the crafted weapons you wanted eventually.
I dunno why Bungie changed this. It seems like a regression to make it strictly RNG.
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When was the last time you played a PsiOps Battleground or completed a Nightmare Containment after unlocking all the weapon patterns? The activity and weapons will be available for at least another 5 months, and that's 20+ weapons with Deepsight Resonance from the Hidden Compartment on top of any that drop randomly from Focused Weapon Spoils+Double Plundered Umbral Energy Map once your down to 1 or 2 remaining weapon patterns.