docs(maker-platform): Tier-5 cleanup — drop duplicate TAM header, date the Etsy stat

- remove the duplicated '**How big is the opportunity (TAM)?**' header
- add the 2023 baseline to the Etsy active-seller decline (~9M (2023) → ~5.6M)
  so the load-bearing stat carries its timeframe (sources in memo §12)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/maker-platform-pr-faq.md

@@ -558,7 +558,7 @@ incumbents stood on each turn into anchors — which is the opening:
   unassailable. The answer: incumbents got greedy and extractive and **eroded their own
   network stickiness**, so a values-aligned alternative can now contest a network moat
   that used to be untouchable. Etsy's reckoning is that erosion made concrete — its
-  active-seller base fell ~9M → ~5.6M as it purged for quality, while AI-generated and
+  active-seller base fell from ~9M (2023) to ~5.6M as it purged for quality, while AI-generated and
   recast fakes flood marketplaces, leaving verified provenance scarcer, more valuable,
   and surrounded by disaffected makers to recruit.
 
@@ -587,8 +587,6 @@ first for four reasons:
 - **"Small businesses are really just people."** Serving makers directly is the mission
   — treat humans as humans — applied where commerce most turned them into accounts.
 
-**How big is the opportunity (TAM)?**
-
 **How big is the opportunity (TAM)?**
 The honest unit of TAM here is **makers, not the dollar size of the craft market** —
 because the platform earns per-maker subscription + referral spread, never a cut of