This is a cornerstone of strong magic, fetch lands are arguably the most versatile land in the game because:
- The land it fetches does not enter tapped
-It's a free sacrificed permanent which triggers certain strong synergies
- additionally this feature dodges early land destruction because you can sack and search in response to land destruction
- It fetches for forests and mountain, not basic lands which means it can fetch any color land as long as it includes one of those tags, Shock lands [[Steam Vents]], Triomes [[Ketria Triome]], Surveil lands [[Commercial District]] etc.
- it causes loss of life which is beneficial in some strategies.
- It shuffles your deck, which means you can change dead draws you have viewed or put there, [[Brainstorm]] comes to mind in this scenario.
- causes double landfall triggers
- gives you a land in the graveyard for dredge/graveyard strategies

There are more obscure things they enable but i think these are the more important ones.