Interesting thread. As has been previously stated, folk who use brifters tend to shift more. Because they are maintaining their cadence, they tend to be a little faster/stronger during long rides. I've seen this with the club I ride with.
As for a conspiracy, Suntour, Shimano and Campy index are not compatible, and that predates brifters. As for some sort of conspiracy to force new bike riders to buy only brifter equipped bikes, Specialized tried a downtube shifter bike last year. The biggest complaint about it, it didn't have brifters.
The reason brifters are found on most new bikes is due to providing the public with what they want. If brifters weren't in demand, there would be lots of bikes being sold by all the big manufacturers without them.
The bike and equipment manufacturers want to sell product, they only manufacture and sell what the public wants.