refactor(skills): drop social proof from systematic-debugging

Real-World Impact was statistics; the Overview opener restated the core
principle as motivation. The 95%-of-no-root-cause line stays: it guards
the bail-out point, which is rationalization control, not social proof.
Supporting Techniques/Related skills untouched (PR #1932 owns that).

skills/systematic-debugging/SKILL.md

@@ -7,8 +7,6 @@ description: Use when encountering any bug, test failure, or unexpected behavior
 
 ## Overview
 
-Random fixes waste time and create new bugs. Quick patches mask underlying issues.
-
 **Core principle:** ALWAYS find root cause before attempting fixes. Symptom fixes are failure.
 
 **Violating the letter of this process is violating the spirit of debugging.**
@@ -286,11 +284,3 @@ These techniques are part of systematic debugging and available in this director
 **Related skills:**
 - **superpowers:test-driven-development** - For creating failing test case (Phase 4, Step 1)
 - **superpowers:verification-before-completion** - Verify fix worked before claiming success
-
-## Real-World Impact
-
-From debugging sessions:
-- Systematic approach: 15-30 minutes to fix
-- Random fixes approach: 2-3 hours of thrashing
-- First-time fix rate: 95% vs 40%
-- New bugs introduced: Near zero vs common