> Linux (probably the operating system you mean) performs terribly when there is no available memory.
I assumed you were talking about system with low amounts of memory rather than well almost all available memory is already used. You might be right about the second case (of course why would anyone have a new Linux PC with just 8GB of memory. Linux laptop OEMs charge the same for an upgrade to 64GB as Apple does for 16GB)
Why do you need to buy the latest macbook with a very fast CPU? Well you wouldn't, if software was more efficient. It's exactly the same argument as with memory.
> doing the same thing my desktop from 2008
Similarly to how your desktop from 2008 was doing the "same" job as a Windows 98 machine? Except it's not really doing the same job, expectations consumers have on software have changed dramatically over the last 15 years.
> well. hardware costs money for us. fix your software.
Yes it does cost money. Because Apple charges extremely high margins on memory upgrades. If you could update your own RAM or if Apple's upgrades had the same margin as the base model itself additional 8GB wouldn't be more than extra $50 (maybe a $100 at most if the memory Apple uses is so 'advanced' AFAIK it's not..).