Quote from Benign:
Well, you shouldn't need to read 3 pages to find the answer. The answer is in the very first post. I stated the reason in the last paragraph, that is:
"[I want to subscribe to third party datafeed only] However the bad thing is IB forces you to subscribe expensive market data if you still want to trade on that market via IB. I say " IB forces you" because it pops up a warning every time you place or change an order, telling you to subscribe market data first before you should trade. The popup annoyance will make you impossible to trade. That's why I said "IB forces you to subscribe its expensive market data", probably to their own benefits."
As you said, IB is not a data vendor. It is a brokerage. That's why its data quality and the plan isn't good. I don't like IB datafeed but I have to use it if I still want to trade at IB.
Ask for clarification if you still have questions.