Why was this downvoted? The swing analogy is horrible. There’s nothing physical that’s going to change when u play the game the exact same way as 04 05 06. The difference is u know what’s going on as opposed to not knowing where anything is. A good analogy would be playing Pokémon red again after beating the elite 4. The game itself won’t be any worse, it just will be easier and maybe less enjoyable if all you enjoyed is the aspect of not knowing where to go. But this is why pvp servers are magical, because each time you level a character, your leveling experience is different based on the encounters that happen while questing. In 05 U may have breezed through stv, but in classic u may spend an hour on a single quest solely because of the competition between factions on that particular quest.
So tonight I took the plunge and thought hey let me buy a Zygor Guides subscription to see how it is. A guide backed by a subscriber base paying for a premium experience this has to be great right? I was wrong. I tested it by loading it up on the Honorboud Rep Guide. Cool it tells me to do World Quests and Island Expeditions. So far so good but hang on... What about the Wanted Quests? Those are by far the biggest boost to reputation. It did not mention them at all. So I thought that's fine it's probably because BFA is quite new. Loaded up a leveling guide on an alt. It was a complete mess. The guide was telling me to accept quests that A) would be horribly inefficient to level with and B) I already done. I also started noticing weird performance issues. Zygor was causing stuttering and FPS dips like crazy. So to close off I requested a refund and the person I spoke to did say I'll be getting one but we will see if that happens. Not getting my hopes up.
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.
Picking up herbalism and mining is the best professions to have while leveling. Not only will you earn gold as you level, but you will also get extra XP. At level 20 you will get over 500 XP for picking up a ore or a herb while killing a mob only gives a little over 100 XP. Don’t go out of your way to pick herbs if you are trying to level quickly, but pick the ones that are on your way. Leveling from 110 to 120 can be done pretty quickly just by doing this. There are a few items that will help you if you decide to use professions while leveling:
Heirlooms: Heirlooms are the best source of bonus XP for leveling. All slots can be gotten pretty easily now, except the rings. The time you need to spend to get the rings if you haven’t gotten a level 3 shipyard in WoW is way too long, so getting the rings is generally not worth it. Having all your heirloom gear will boost XP by 55%. Generally, you want heirloom gear with crit on for leveling as you want to kill mobs in a few hits as possible
Other methods have been discussed. For example, mods could be crippled. DBM didn't exist back then, and the other boss that did that I don't remember the name of, didn't do as much back then as DBM does now. If our goal is to recreate the experience as it was, then obviously not having DBM would be a reasonable way to accomplish that. DBM simply existing, makes the game today easier than it was. So disallow it. Again, this is completely consistent with the spirit of vanilla. Remember one-button-decursing? That was nerfed. They crippled the capabilities of the modding API to disallow that because it made the game too easy. So what if they cripple it a little bit more to once again make the game less easy?
War Mode: War Mode can be turned on at level 30 through your talent window, and will give you 10% bonus XP. You will, however, be attackable by players of the opposing faction, but changes have been made so that all players have a fair shot in a fight and even low-level players can kill much higher level players, and at least not get ganked and one shotted. Note: As of patch 8.1, you can get an additional call to arms bonus with war mode on if your faction is underepresented.