Other people have noticed that Microsoft licensing their OS to the computer manufacturers has played a massive role in it's dominance of the market. Apple had the option of either licensing their system to 'clone' manufacturers, or to keep it exclusively for their own hardware. Ultimately they ended up going along both paths - exclusivity for the early 1980's and the latter 1990's to today, but they licensed it for a large chunk of the early 1990's. And look what happened - Apple was on the brink of collapse during the latter Sculley/Spindler period. If anything, it was Sculley that made the mistakes that lead to the rapid decline in Apple's market share, long after Jobs had left and created NeXT. If Apple had chosen the route that was successful for Microsoft - to license their OS to other computer makers - then it's possible (and probable) that people will consider OS X to be as "clunky and glitchy" as Windows (yes, that is a subjective comment, but it seems to be a rather popular view). As has been noted, Apple has recovered amazingly since Steve's return, and Macs are gradually gaining back market share from Microsoft (the fact that last quarter was Apple's most profitable EVER says it all).
In short, I'm confused as to how Jobs is, apparently, to blame for what happened to Apple. The huge problems didn't start until well after he was out of the picture. Blame the lolly water maker.