Borrowing Cap history:
- Proposal 26 set the Borrow Cap Guardian to be the Community multisig
- How the Community multisig manages the Borrow Caps was established in Discord / forums
- Proposal 27, which added COMP support, set the initial borrowing cap to 50k COMP; the discussion around the 100k borrowing cap ceiling was a Community multisig discussion in Discord if I recall
The Community multisig is empowered (at a protocol level) to set these limits; if there is a strong community consensus, I don’t think that it needs to take place through an on-chain formal proposal.