Taking "amateur" as someone who does something for love rather than money, I could argue that it's the professionals who could use that argument with far greater force. And assuming that if professionals do it (and they do) that they have a reason, it's not hard to guess what it is - it gives a better result. Should amateurs love the creativity of photography enough to make the effort to produce the best photographs that they can? I'd say yes - but see below.
Whatever you do, there's a limit to what can be captured in 8 bits. You will always lose details in highlights and shadows, which has to be thrown away to create the jpg. Do these details matter? Perhaps not every time, but certainly some times. And those times are the ones when it's impossible to "get it right in camera" if by that you mean the resulting jpg. Now, if you mean the raw file - well, subject to the limitations of cameras, lenses and sensors - you can at least aim to get the right starting point for the final image.
Different people "do" photography for different reasons. Some just enjoy being out with a camera and use it as a notebook to capture memories, and for them arguably jpg is all they need (for the moment - if they move camps they may later regret that they have severe limitations if they want to produce a better print or on screen image from an old photograph). Some enjoy sitting at the computer and manipulating images (I expect some painters are happy indoors daubing paint on canvas rather than being outside). And some concentrate on the final result. I'm in the last group, and my aim is to get the best starting point in camera for my final image. It's very rare when I use film to be able to do this, and impossible when when using most digital cameras (I produce black and white as my "native" output).
Edited for typos.
