Not the first time I've spoken about this so I'll repeat all the usual points.
1) It was one of the first novelizations of the first (and sequel) movies, and to this day even though it's stalled at the Saurus Rock adaptation for years this series still made it the furthest in terms of covering the film series with consistent quality.
2) Practically was the Trope Codifier for the "human character time-travels and falls into LBT world to meet the gang isekai" trope. I don't think it was necessarily the first, but the first Retold story did it better, was rather well-written, and was considerably widespread that it garnered that reputation for any story that came after. You can check the 2013-2016 era when Retold was at its peak and had more consistent updates, lots of those kinda stories came in its wake. Many in those years played it straight and used the general concept of meeting the gang in the initial journey to the valley, but a few took a little more liberties with it. This trope has considerably died down nowadays, but when Retold was at its prime you can bet there were all sorts of copycats.
3) Not a one-to-one adaptation. Small changes and added scenes (usually with the POV human characters which are all new) and the addition of said human characters change things about slightly. Indeed, many of Retold's best scenes are the ones that aren't actually adapted from the films, but are the parts expanded from it. That added lore and originality is what draws people back, because if it was a 100% novelization then why not just watch the movie? This is what gives the series an air of unpredictability, and coupled with a fair bit of cliffhangers for many readers and reviewers to ponder just what might happen next, even though in your head it's like
"isn't this an adaptation of something I've watched so I should know how it goes?".
4) Being written in the early 2010s when LBT fandom was much bigger, it received a loyal following by catering to the three points above. Seriously, if you garner TV Trope editors to make a page for your story without prompting, you're up there. Even despite the inconsistent schedule and recent massive hiatus and actually losing much of the influence it has on its heyday due to different writers nowadays preferring
not to go the "human in LBT" route now, it's still consistently popular because the author has her loyal fans invested into said OCs she made and the slightly different of a LBT world with a couple added humans here and there.
All in all, it's all pretty indulgent stuff, and even
I, angsty no-fun edgelord that I am with this series, kind of like the indulgent part of it. Who wouldn't? Get to Stone of Cold Fire already! I've been waiting for years!
tl;dr: could be chalked up to a fic series being at the right place at the right time to create a formula and gain its loyal following.
Do I think it deserves that following? Of course, why not? Do I think it could also be better in quality considering the disproportionate jump in favorites and followers compared to authors who try just as hard with different takes on the franchise but get shafted? Also yes.
Judge the series as an adaption expansion on its own merits, not on perceived popularity by the follower/favorite count.
