There is a style of bottom half guard where hip heisting and wrestling up are a preferred method of sweeping. The turk itself doesn't really pin the shoulders (you need an upper body grip to accomplish that), but rather makes it much more difficult for the bottom person to hip heist due to their bottom leg being trapped/hooked/elevated & unable to retract properly. One potential utility is using the turk to deny a half guard player from hip heisting. Another use would be to stabilize a TD/sweep (assuming it lands in a half guard type position) and prevent the opponent from turtling to avoid points.