Its the same reason why Kodak invented the first digital camera and didn't put it in the market. We see the same pattern over and over again and if you work at any of these huge corporations, you understand that the main duty of the executives is to protect their profit centers at all costs. Any product that is capable of cannibalizing on the profit centers will face a tough road to success and at the worst, get culled early.
Then a startup comes along, reinvents or polishes that product and is very successful. Eventually it turns into a BigCo. And the cycle repeats.
