Sure, but the point is that SmartThings has an IFTTT channel as well.
So you use all the ST logic you want inside ST. It’s just that for the last step instead of communicating directly with the WeMo maker, you turn on a virtual switch. You use that switch going on as the IF for IFTTT and the WeMo Maker as the THAT and they’re linked.
If, as I personally would suggest, you get the purpose built garage door controller off the official “works with” list (manufactured by Nortek, but sold under several different brand names including Linear, gocontrol, and one of the Nutone models)
http://www.smartthings.com/compatible-products
You could still use the same method to connect to your WeMo maker for other purposes. Actually, use the same method to connect to pretty much anything that has an IFTTT channel–it’s one of the very powerful open platform features of SmartThings.