The development of PHP is community driven by the RFC process described in this document. Anyone may initiate an RFC for any subject. At the end of the RFC process a vote is held among PHP developers to determine if the proposal is to be accepted.
Should a proposal be accepted, the developers of PHP are committed to making the change.
In some circumstances, merging an implementation into the source code of PHP may be delayed because of shortcomings in that implementation. In these cases, resolution of these shortcomings is the responsibility of the proposer.
Should a proposal be accepted without an implementation, it is the responsibility of the proposer to provide one.
My understanding is as follows
First paragraph: as a part of community everyone can propose an RFC and push it on discussion but the PHP developers hold the right to accept or reject the RFC.
Second paragraph: When RFC is accepted PHP developers are commited to provide an implementation (author or other PHP developer who volunteer) and merge patch.
Third paragraph: Merging can be delayed due to bad code or conflicts and it's the responsibility of proposer to solve that issue.
Last paragraph: If the proposal is accepted without implementation proposer responsibility is to provide one and ask for meging it.