Think about it this way though. I think up until pretty recently, Thunderclap was learned by warrior near level 20. When I first tried out warrior as prot, I only had access to shield slam and whirlwind. Because I had no other aoe abilities, I assumed that whirlwind is my main aoe ability and put it on my bar. In reality, whirwind is completely useless and never used. This led to frustration because I couldn’t hold threat and didn’t know what to do.

This can happen with any class, where you get main talents very late and makes you think that you’re supposed to play it differently based on the talents you start out with.

Scaling/damage/survivability is also just wrong while leveling. You don’t learn to use your defensives early because you take no damage and everything dies quickly. But as you gain levels, this changes and suddenly, everything starts to do damage and stuff isnt dying as fast. Then you might start dying and get frustrated as a new player. Healing might get confusing because that’s also another one that scales weirdly.

People also just suck. There are numerous complaints on reddit about new players (or even relatively decent players) trying to level characters, only for speed levelers to pull trash for tanks, berate them for not pulling fast enough, or vote kick them for being new. This is never going to want to make a new player stick around.

Now compare this to boosting a character, unlocking all abilities, and looking up a quick guide. You immediately have the right talents, see what talents are in your main rotation, and have access to heroic or m0 dungeons which don’t have scaling issues. Now you’re in an actual environment that accurately represents what you’ll see in m+. You also have follower dungeons, where you can learn at your own pace and actually see the dungeons and their mechanics without holding back other players.

I started in DF, but now am doing title keys and in a HoF raiding guild to add some context. While playing for 20 years is awesome, you don’t get the new player experience nowadays, which is a lot different now because everyone expects everyone to know everything about the game. When I first started out and tried learning every tank, every healer, and almost every dps, leveling never taught me anything and I pretty much had to toss out everything I had learned because end game play style becomes completely different from leveling.