If the Amiga did not stun the world in 1985 with concepts like multitasking, more colors, animation, stereo sound, hardware assisted accelerated graphics and more would computers be a good as they are today?
Probably not.
Sadly, I think that is not true. Amiga was ignored by pretty much everyone in the PC industry. They simply called them toys, despite the fact that everyone else was building inferior machines for a while.
Macs didn´t include multitasking until Linux had become a hit. PCs didn´t have real sound until Yamaha and Roland were entering this market. None of them had custom chips on the main board and Multimedia and DMA were "inventions" of the 90s. Steve Jobs even faked his first CD-quality-sound Demo, because NeXT couldn´t do it in 1988!
Business wasn´t getting Amiga and they weren´t even looking at it. It was the hobbyists who bought them and only video-professionals on a tight budget would realize their potential.