@ Ian Joyner - IBM relied heavily on the myth they were the best computer manufacturer for decades. The fact they always had clay feet is not surprising to those familiar with technology but that is not who they were marketing to. They were marketing to the era's PHBs & MBAs who did not know how a computer worked at all.
Part of what did them in was the shift to PCs and networks which allowed people to actual use a real computer for tasks no one would ever use a mainframe for. In the 80s & 90s they had a schizophrenic relationship with PCs; too afraid they would cannibalize minis and mainframes and would not put enough emphasis on PC based systems. What happened is others pushed PC based systems and killed the mini computers and put a dent into mainframes.
Also, consider that one might own several different computers including smartphones and tablets that are in many respects more powerful than mainframes of 20 - 30 years ago. And these devices cost <$1,000 each compared to many orders of magnitude more for a mainframe.
There is a strong parallel to Slurp, similar myth and marketing strategy; the myth they are technical leader and selling to PHBs and MBAs. A strategy that works only a period of time until there is major shift in how business and computing is done.