The devs cannot alone make these types of changes, it's up to the witnesses to approve and upgrade to the latest hardfork to approve and accept these changes.
The witnesses are an elected group of 20 individuals, voted in my the stakeholders. You could probably argue that's not decentralized enough, but it is decentralized.
The witnesses approved HF19 - so the changes went through.
twenty withnesses right?
The witnesses refused to accept the previous hard fork, until some changes were made.