He's complaining that Blizz resets all the tasks if you don't finish everything during that holiday period, ie if you did everything for Midsummer except for the torch juggling bit, next time around you have to do every single necessary Midsummer achievement again to get the title, not just the torch juggling.

Is that a new thing? I've never experienced this, although I got my Year-long achievement back in Wrath.

The only time that happens is when it's a single achievement with multiple steps. Elders of Kalimdor comes to mind. If you got to several of the elders, but not all of them, then next year it resets and you have to get them all to get the achievement.

Once any single achievement has been obtained it stays in the logs, and you do not have to get every achievement in the same year to get the meta.

For Midsummer, if you did everything except Torch Juggler one year, the next year all you have to do is Torch Juggler, unless something new is added to the meta. You do not lose the "Flames of Whatever" achievements unless you never actually completed them, in which case you never had the achievement in the first place.

This is amazingly annoying on those of us with limited playtime, and part of the achievement requires doing X action, which gets you a 1hr cooldown before you can do it again. Even the fed-ex (Elders, Candy buckets) are so much better than them. Because of the general upending of everything over the Christmas period, I still haven't gotten the snowflakes achieve, because I think I got to /kiss a reveler about 6 times total each year, and only gotten 2 lots of snowflakes, and the blasted thing keeps resetting!!