Routing is a Layer 3 issue. Loops are a Layer 2 issue.
Multiple paths on a Layer 3 network provide redundancy when used with a routing protocol such as BGP.
Multiple paths on a Layer 2 network provide redundancy when used with a protocol such as LACP. Without proper design, 2 network segments connected with multiple links will trigger Spanning Tree and shut down one of the links. And depending on the configuration, it may or may not unshut if the active link pair goes down.
Also, it's allows loops to be used as multi paths from different points in the net. Say you have a rack at south and north and there is a loop to a rack in the middle. For failover, you'll take any path that is up. But for normal operation, you'd prefer to take the shortest path.
Multiple paths on a Layer 3 network provide redundancy when used with a routing protocol such as BGP.
Multiple paths on a Layer 2 network provide redundancy when used with a protocol such as LACP. Without proper design, 2 network segments connected with multiple links will trigger Spanning Tree and shut down one of the links. And depending on the configuration, it may or may not unshut if the active link pair goes down.