Help Leatherworking Specialization Dragonscale Tribal Elemental - New play

Hi,

Me and two of my friends are playing WoW for the first time in our lives.

I'm having difficulties understanding how the Leatherworking specialization works, as some guild members told me that it doesn't matter anymore and I can still learn Dragonscale/Tribal/Elemental regardless of what i specialized in.

More concrete, I'm a level 51 Hunter, finally managed to level up my leatherworking enough to specialize, I'm specialized in Tribal because yt and other info but I realized I much prefer the Dragonscale pieces.

We're mostly playing alone, doing dungeons and questing.

Is it true? It doesn't matter what I specialized in, I can still learn Dragonscale?

If that is true, did i just waste materials doing that Tribal questing for that very basic tribal set?

Do I even need to specialize?

To make matters more confusing the Alliance trainer in Azhajra (close enough) thought me how to do Dragonscale Breastplate and I'm Tribal.

Thanks.