The original World of Warcraft was released in 2004, and World of Warcraft Classic aims to recreate the state of the MMORPG before its first expansion, The Burning Crusade, was rolled out in January 2007. Previously, players looking for a “vanilla” version of the game were only able to experience it on custom servers such as Nostalrius, which Blizzard shut down in 2016 to protect its intellectual property.
Within the context of Classic, the method most frequently proposed is to re-tune bosses to make them harder. Rather than copying the numbers, re-create the relative difficulty. Kind of like, when you first start working out, you use small weights. When you get stronger, you lift bigger weights. The WoW community is more knowledgeable, more experienced, has better hardware, etc. We're "stronger." So give us tougher bosses. There are a lot of forms that could take. Bosses were constantly re-tuned during vanilla anyway, so if Ragnaros does 10% more damage or something, is that really a problem? I don't think it is. What about resistance gear? back in the day, collecting resist gear was a thing people did. But the numbers and strategies are so well known today that only the tank really needs it anymore. Bosses could be re-tuned with more resistible elemental damage so that's important for entire raids to gear appropriately. That would be entirely keeping with the spirit of vanilla even if the actually numbers sitting in a database somewhere were different than they were ~13 years ago. If you want to go a little farther, a few people have proposed adding new abilities to old bosses, adjusting their timing, etc.

The vanilla WoW Horde leveling guide you see on this site was originally made back in 2006 by Joana (AKA Mancow, or FuriousPaul).  The guides have been tweaked many times over the years to make things "faster".  The leveling guides were made because of all the messages I got from people asking me how I was able to level up so quickly on new realms.  I was first to level 60 on 7 different realms (3 with Mancow and 4 with Joana), even winning Blizzard's "First to Level 50" contest they held back in 2006.

So far i've done almost half in the past 2 weeks or so. I just want to know would it actually be beneficial to do the above tasks? Just all seems a bit too grindy, I feel like I've been wasting so much time doing old content that's not even needed any more... but I didn't mind doing them for the transmogs and such. I guess i'm just asking if this addon is really worth using and it's not suggesting unneeded filler.
You’ll get a small window inside the game with instructions for what you need to do next, every step of the way to 120. You’ll also get a waypoint arrow that points you in the right direction to go at all times. If this sounds extremely convenient, you’re right! Zygor’s leveling guide/addon has completely taken the frustration out of leveling for me, personally. No more reading comments on WoWHead about how to complete quests. No more getting stuck, frustrated and bored with leveling. And no more feeling like WoW takes too much effort.