More than other games, MMO experiences have a time stamp because the game itself changes and our experiences with the “same” piece of content might be radically different.
This is especially true in the early days. Yesterday’s dungeon discussion had some sharply divided experiences, and those could be caused by class, gear, strategy, or the dungeon’s having been updated a half-dozen times in a month. I finally tried WoW so I could see how the zones looked before the Cataclysm revamp only to find that the veterans’ experiences were radically different due to other changes that had accumulated over the years. My trip through Guild Wars: Prophecies included heroes, lots of elite skills, and PvE skills, which changed everything even if none of the Prophecies content had changed.
As a LotRO player, I recall approaches to Moria boss fights that went from “standard practice” to “exploits we patched away.” Sometimes you need the good bugs to get past the bad bugs. Some grognards talk about how hard X was during their day, and some of them did Y while it was easier, broken, bugged, etc.
The population shift is also a big change over time. The original wave of Warhammer Online players experienced public events 1.0 as intended, but as early as a month later many zones were ghost towns and you never saw the last event phases. In September 2012, players bemoaned that the Guild Wars 2 economy was broken because scraps of jute were very expensive. Come September 2014, players may bemoan that the Guild Wars 2 economy is broken because craps of jute were almost worthless. It seems to be a rare event for a game to maintain a steady population spread rather than having huge clumps at the top and bottom levels.
“Trammel” and “NGE” are extreme cases you need not mention. Everyone knows to distinguish between before and after those chasms.