I don't think there is anything wrong with saying, you just have to have the right device for the right task. If what you need is to check email and browse websites, get something that does that. It might do more, but if that's all you need, than it doesn't have to do more. Likewise, if you need a "very specific genealogy application" then you know you have to get something that runs that. Just because some customers need something specific doesn't mean that everyone needs something that can do everything. You just need to find the right thing fo the job.

Case in point, I have a friend who was going on a multi-year trip to Australia. She wanted to get a computer that could travel with her, run skype, let her update her blog and upload pictures. Other than that, she didn't need anything else. She may do heavy picture editting on her Macbook at home, but she realized for a trip like this, all she needed was a netbook with linux on it. She got skype and webbrowsing, and the ability to pull pictures off of her camera. She realized a full Macbook or Windows laptop would've been overkill, so picked the right tool for what she needed.