The syntax had been proposed long before then; I (along with others) had been advocating for it the prior year. The May 6 blog post was merely the point at which the blog post author relented to the rest of the lang team to bring it up for a vote.

As for your second sentence, RFCs are almost always accepted before they are implemented. There is an entirely separate round of review and approval before an accepted RFC can become a stable feature of the language.

> As for your second sentence, RFCs are almost always accepted before they are implemented.

That's fine when * RFCs are not controversial * RFCs does not change much before stabilisation

> The syntax had been proposed long before then

Let me rephrase it this way. It was only a couple of weeks when syntax became available in nightly before the final decision was made.