That's a particularly uncharitable way to put it. Another way to put it is this:
Regulations encouraged a fragmentation in exchanges (a good thing, since they used to be monopolies).
For multiple exchanges to trade in the same instrument, some force needs to synchronize the prices between the markets.
The regulations specify a mechanism by which this might work: quotation feeds for different products replicate the NBBO ("current" best bid-ask) across the markets.
But the NBBO feed is only an approximation of the best feed --- and it has to be, as anyone who has ever built a distributed system must know.
Fast electronic trading can synthesize a BETTER NBBO. If you know what the better NBBO is, you can trade against it, in effect forcing prices to synchronize through arbitrage trades.
The net effect is that the markets synchronize on a more accurate BBO, and electronic trading systems get compensated for doing this based on the profits from the arbitrage trades.
In the ABSENCE of that trading, the delta between the SIP NBBO and the "real" NBBO still exists; it's just money in the pockets of a different set of entities.
In neither case was this money likely to be helping firms that hold long-term positions and make money by allocating capital; the previous crappy NBBO profits were just going to a different set of sell-side firms, who are now angry that they'd been obsoleted.
To me, an extremely telling fact here is that Vanguard's Chief Investment Officer went on the record and said that HFT trading, and latency arbitrage in particular, had been helpful to their trading costs. If that doesn't mean anything to you, do some research into how Vanguard works and is structured.