ipip-462: expand alternatives

https://github.com/ipfs/specs/pull/462/files#r1492982484

src/ipips/ipip-0462.md

@@ -82,7 +82,13 @@ more than once MUST also set limit (e.g. max 3) to avoid abuse.
 
 ### Alternatives
 
-N/A
+- Why not just an arbitrary identifier the user could use to establish a
+  relationship between requests?
+  - Requires server to keep state, which breaks or complicates gateway
+    deployments with horizontal scaling.
+  - Does not help when client is sending requests for different blocks/sub-DAGs
+    to different trustless gateways, and none of them has the whole picture,
+    and majority of them do not know what is the parent content path.
 
 ## Test fixtures