The IETF has a two-level standards system consisting of "Proposed Standard" and "Internet Standard". IPv6 was first published as "Proposed Standard" in 1998 and finally transitioned to Internet Standard in 2017. Although officially Proposed Standards are supposed to be treated as "immature specifications", as a practical matter, people routinely deploy on them. Whether an RFC is advanced to Internet Standard is less a question of whether it is mature than whether the editors and/or WG bother to advance it. Here are a number of examples of widely deployed protocols that never advanced beyond Proposed (1) all versions of TLS (2) HTTP/2 (3) SIP (4) QUIC.
I think choosing 2012 as your start date is pretty generous. Proponents of IPv6 were telling people to start deploying long before that. In fact, the IETF sunsetv4 WG, dedicated to sunsetting IPv4, was formed in 2012 several months before World IPv6 launch day. Arguably, World IPv6 Launch Day was a reaction to the failure of v6 to get large-scale organic deployment 12ish years in.
The IETF has a two-level standards system consisting of "Proposed Standard" and "Internet Standard". IPv6 was first published as "Proposed Standard" in 1998 and finally transitioned to Internet Standard in 2017. Although officially Proposed Standards are supposed to be treated as "immature specifications", as a practical matter, people routinely deploy on them. Whether an RFC is advanced to Internet Standard is less a question of whether it is mature than whether the editors and/or WG bother to advance it. Here are a number of examples of widely deployed protocols that never advanced beyond Proposed (1) all versions of TLS (2) HTTP/2 (3) SIP (4) QUIC.
I think choosing 2012 as your start date is pretty generous. Proponents of IPv6 were telling people to start deploying long before that. In fact, the IETF sunsetv4 WG, dedicated to sunsetting IPv4, was formed in 2012 several months before World IPv6 launch day. Arguably, World IPv6 Launch Day was a reaction to the failure of v6 to get large-scale organic deployment 12ish years in.