[dontbelieveyou]

> it's obvious that Proof-of-Work has not been used to decide consensus protocol parameters

Every "soft-fork" to date has used PoW to activate new consensus rules by requiring block version super-majority.

[kanzure]

> Every "soft-fork" to date has used PoW to activate new consensus rules

Consensus rule parameters are things like "max block size". However, there have been some proposals for extension blocks to increase block size without requiring a hard-fork (e.g. using a soft-fork mechanism).