Four life per connection which can be as much as 8 life per turn with re-equips for blocks or double strikers is a fair old chunk
You can manipulate the top of your deck with cards like Worldly Tutor and Mystical Tutor, so Rashmi's ability doesnt just draw a card, but spells like Mystic Confluence and Torrential Gearhulk replacing themselves on your opponents turn is often plenty of value
High-grade examples demonstrate substantial premiums
Its a heavily-played card in formats where its legal, and thats mostly Vintage, Legacy, Cube, and EDH, where its a Game Changer
While this mirrors Circular's effect, Gate Magician unfortunately does not fully start our combos, as this requires a "Supreme King Gate" card, other than another copy of itself, already scaled to activate
Notice that these are general deckbuilding/gameplay tips that apply to Magic in general and not just ward in particular