No, it's because the software they write has higher requirements than computers at the time can provide. They bite off more than the hardware can chew. And they already know exactly just how much the hardware we have can chew... yet they do it anyway. You write stuff for the hardware we have NOW. "The hardware is not fast enough" is never an excuse. The hardware was there first, you write software for it. You don't write software for nonexistent hardware and then complain that the current one isn't fast enough. The hardware is fine (it always is). It's the software that's too heavy. If you don't have enough compute power to render that particular effect... then maybe don't render that particular effect and take technical considerations in your art style.
