I can see there being a happy medium here as no all support requests are task oriented. Either a) asynchronous support for support inquiries like "When will product x be in stock?" or "What does policy y mean to me?" where as "How do I setup email on my phone?" could be handle synchronously. or b) begin asynchronously and move to synchronous communication as needed.

At the very least both options should be offered. I almost exclusively use text-based communication unless it's a time-restricted request. This works well for Simple (the bank) where I tend to have a lot of financial questions that I don't need answered -right now- so I shoot off a quick message and follow up if needed; however I've had a couple of situations that required immediate answers and response and those times I absolutely picked up the phone.

Having worked in tech support for two major telecomm companies though, I'm convinced it's most commonly a problem of formatting. The discrepancy between instruction and reality is what throws non-technical people off. Given accurate instructions your grandpa could figure it out at least 75% of the time. One of the companies placed extreme emphasis on their resources with the reasoning "They'll figure it out." and according to them and their metrics they seemed to think most people did figure it out by braille if you will.

Just my two (or more) cents.