The NYSE has always required market makers continuously buy and sell the stocks they specialise in. They must do this in all market conditions, even if it means running a loss. In exchange, they get privileged access to order flow information. This is why those seats are valuable. NASDAQ challenged that model by removing the physical trading floor. Instead of humans standing in a pit there were humans sitting behind screens. But in both cases there is an institution guarding access to the market's nerve centres. Barriers to entry were raised and the incumbents protected.
HFT takes the abstraction one step further. Democratised is that access to privileged order flow - anyone who can pay can get it. Lost is the role of a designated market maker - HFTs can pull out when markets get rough. This is a valid debate.
But don't confuse yourself. The order flow privileges being criticised have always accrued to institutional market makers. It is no surprise that those incumbents are the ones driving the present lobby.