The Amiga was hardly a low end computer. I bought a 500 in 1989 and they were wonderful machines. The high end systems could run Unix and were used in commercial video production. You just can't compete with platform effects though, and there wasn't a gap in the market between the Venn diagrams of the PC, Apple and Linux behemoths. In the end not even Sun could make a go of it.
I think what was meant is that Amiga’s market share was predominantly in the home computer space. And its software catalog consisted primarily of video games rather than productivity software. In that sense it was low end.
It was wedged between game consoles and PC’s, and it eventually couldn’t compete against neither.