Not having weakauras doesn’t put you at the disadvantage.
It’s just a lazier option to keep track of things.
One of my better ingame friends is one of the best moonkins in EU and he doesn’t use weakauras, or more than like 3 addons in total or something of the sort.
He tracks everything manually - his buffs, debuffs, eclypses, when people are bursting, if he’s in an Earthen totem or not, if hes given a defensive by his healer, etc.
He’s just used to it so he doesn’t need them.
Many people think they need weakauras but oftentimes when they remove some they don’t even notice the difference.
A lot of people even handicap themselves because they clutter their own screen with useless information thus reducing their game sense even more.
So it’s just a choice thing.
I personally mainly just use ones to keep track if I get enchant or talent procs and stuff like that, simply because I don’t want to look at the top of my screen where my buffs are. I make them myself most of the time as it is extremely easy and simple to use after you try the addon’s functionality for like 20 minutes.
The Mes Weakaura, which notifies you when big CDs are used, is just a louder version of the ingame sounds.
When you pop Wings, there’s a sound to it, but it’s not loud enough most of the time. The Weakaura plays the same sound, only louder. Same goes for things like Icy Veins, Observer, The Hunt, Ray of Frost, etc. The text on screen is optional if you want it or not, most good players just use the sounds to avoid screen clutter.