Why is HIIT cardio better for body builders?

Why is HIIT cardio better for body builders?

I have recently switched to HIIT cardio (22 minutes) 3X a week as opposed to doing a 4 mile run 3X a week. Why is this more beneficial to someone trying to build lean body mass? Thanks. Here is my HIIT cardio on a treadmill:

Minute/ Pace
1 8:30
2 8:30
3 8:00
4 7:30
5 7:00
6 6:30
7 8:00
8 7:30
9 7:00
10 6:30
11 8:00
12 7:30
13 7:00
14 6:30
15 8:00
16 7:30
17 7:00
18 6:30
19 6:00
20 8:00
21 8:00
22 8:00

I dont know about body building, but for generally losing fat... I lose more fat when I do HIIT instead of normal cardio.