Jobs had a long-term vision in the future of Apple as a consumer electronics company, as opposed to a techie company. The explosive growth of Apple in the 2000s and 2010s would never have happened if Apple hadn't matured out of being the company that made the Apple II line.
Jobs is the one who killed the Newton when he returned.
Apple could have launched in iPhone like product years ahead of when they did if they kept that branch of the company afloat. That would have been a real 'visionary' move. Instead, they were forced to differentiate themselves in a crowded marketplace by emphasizing little design flourishes and style.
Job's only real contribution is managing to gaslight (a.k.a, his "reality distortion field") the entire industry into thinking he had any real insight or ability beyond that of a typical middle manager with a cluster-b personality disorder.
Computer companies getting into consumer electronics is a result of average consumers wanting devices that behave more like and interact with computers. It's not the result of some messianic insight that no other company had.
We can't speculate on what a Apple Prime would have done without Jobs. But we do know that his single mindedness about making arbitrary changes cost them several years in the 80s and led to the slump in to the 90s.
I wanted a IIgs when I was younger, until someone told me about the Amiga. I also looked at the Atari ST. They were both cheaper and much more powerful. (I went with the Amiga. )
You are right. The CPU speed was lame. They also dragged their feet giving the IIgs a decent OS. If they released a souped up IIgs (Apple IIx or whatever) back in 1984, do you think the Mac would even exist?
It would have been exposed as being a dead end with no backwards compatibility. The GS was essentially a completely different architecture from its predecessors anyway. Compatibility was maintained with the Mega2 chip. Apple wouldn't have been stuck for a couple of years with barely any software on their "flagship" product.
The GS would have killed the Macintosh if they raised the clock speed, gave it some higher video resolution modes, and developed something like the Macintosh Toolbox in ROM for it.
If that is true, then I appreciate him more as business man and leader. The 2 GS was late to the game and a dead-end. In '83 us geeks would have killed for that machine, but in '87 after Atari ST and Amiga were released two years prior?