100ms more is absolutely enough to be massive because it just subtracts from however long you need to recognize the other player after they become visible. Not to mention that in slower paced shooters, people might just remain stationary near a corner for very long, and you can’t magically know when they start to move. Also in games where you can die with one well placed shot it could be 10ms and still be a significant advantage because you just need to be faster than your opponent.

Afaik valorant does try to not send any info that won’t be needed, that doesn’t mean it’s immune to wallhacks, it just limits their effectiveness.