What knowledge points do for?

Which could short explain me about this.
I’m still dont understand about knowledge points.

Before I late return one year later DF and saw new thing. Dont have level full. Now TWW still same but seem changed. Try understand…

  • miner, skinning and herb with knowledges for? Make easy find rare drop?

  • engineering, leatherworking, ect… what KP make? Make more stronger gear?

With KP you can fine tune your professions to find more, rarer, or craft better gear indeed.

There’s a short preview window once you unlock the specialisation to inspect what each unlocks you.

I understand, thank you.
(sorry poor english)
But, I’m wondered why knowledge points reset after DF over and again farm KP in TWW.
How players hard time farmed and maxed all specialisations ago in DF and lost every.

Because DF prof specs don’t matter in TWW. New expansion, new mats, new specs!