Not true, I've done this a couple of times. It may not be the cheapest ticket, but it can book into S at ~RM600 if the return is on MH metal.

I agree 30mins is not worth it for everyone (realised it's a 7:35am flight, only 30mins earlier than the MH flight), but for someone who has 9:30am or even 10am meetings, it helps immensely.

Also, while I normally travel w/ no check-in luggage, I've previously convinced a ground staffer to interline bags given they're both MH tickets, even if on SilkAir metal. (Of course, the one time I did that, the flight was delayed 2hrs, meaning I was unable to check-in @ KUL, and missed the flight....)