So committed, in fact, that modern WoW players are trying the beta and reporting what seem like bugs today but what were actually intended functionality 13 years ago. This became such a common occurrence that Blizzard publicly posted a list of known non-issues called the "WoW Classic 'Not a Bug' List." For example, hitboxes for the Tauren player race are much larger than those of other races. In a modern game, this would be seen as a serious balance issue (see: Apex Legends). But it's what vanilla WoW was like, so it has been faithfully reproduced.
One player said in a comment posted in response to the list, “Yeah people don’t realize the sheer enormity of game system evolution WoW has gone through since release. I’m not the biggest fan of BoA by any stretch, but I’ve played since closed beta vanilla, and I doubt I’ll be going back to classic. Leveling was painful. Experiencing these old systems once was enough.”
Blizz stated in a watercooler that they're using the 1.12 database as a starting point. I don't think it's a stretch for people to assume that most game features and mechanics will be in their 1.12 state. The kind of stuff I would expect to see reverted would be numerous AV changes, but I seriously doubt class mechanics are going to be reverted. I'd be surprised if the threat changes that ruin pre-naxx encounters are reverted.
Making "new" guides seems kinda out of place. Not only is there still alot of information from back then available, there came alot of information up for minmaxing available for both leveling and raiding, ontop of various bis gear lists that cover patch progression aswell if necessary. Wether people like or dislike pservers does not make the various information found on their forums less valuable.
Blood: Unholy Command - Your Death Grip has two charges. Frost: Chill Streak - Deals up to 6% of the target's total health in Frost damage and reduces their movement speed by 70% for 4 sec. Chill Streak bounces up to 9 times between closest targets within 6 yards. Unholy: Necrotic Strike - A vicious strike that deals [ 30% of Attack Power ] Plague damage, and converts 1 Festering Wounds into a Necrotic Wound, absorbing up to 7% of the target's maximum health in healing recieved. Demon Hunter
It is also worth noting that World of Warcraft Classic isn't exactly an archive from 2006. It has been rebuilt from patch 1.12, using modern data architecture and reaps the benefits of the modern engine. This means a lot of non-controversial quality-of-life features will still be present and it is possible to run WoW Classic servers on modern server architecture. As you can imagine, much has changed in the last 13 years in the tech space. That's before smartphones were even a thing. The modern engine no longer allows certain behaviours that could be used to get out of bounds, also adds widescreen monitor support and accessibility options! However, it does have the disadvantage of not being able to run on 32-bit systems which isn't that kind to older systems considering the game is from 2006.