Also if you do go COTS and don't do the business change to fit the product. Trying to make COTS work your way is always so so so bad.
Starting off with a complete custom set-up for your core is another opportunity for premature optimization to creep in.
So what then dawns on the business is they realize that the missing 10-20% was part of the business that was really important and they have dropped serious money on a bunch of products. And really all they needed to do was better understand themselves and build their own business infrastructure.
But what you are saying about speed definitely rings true. But it's important to note IT failures that happen to new businesses are more or less written off as total business failures Usually resulting in the business going to the wall.