Let's say you're only allowed to trade once a week, and I buy a bunch of Hooli stock at, say, $25 today. Then they launch Yet Another Hooli Chat tomorrow and everyone has decided that's going to make the price go up. You might want to buy some shares at $27 right now, because you think they'll be worth $30 next week. And maybe I want to see my profits right now for whatever reason (maybe I worry about them shutting down their new chat service by next week and I have a very low risk tolerance) and I'm happy to see some profit now instead of maybe more profit next week. Obviously I should sell to you. I can't do that via NASDAQ because we can't trade again until next week, but if you and I are in contact, we can just trade privately ("over the counter").

If lots of people start doing that, and we all join up, we essentially become another stock exchange. So it's not in NASDAQ's interest (or anyone's, really) for them to voluntarily stop doing things that will just cause another stock exchange to exist that does those same things. The options are either to convince market participants that the new rules are actually going to be better (more profitable) for them, or to lobby for regulation that makes the old rules impossible for someone else to implement.

As I understand it, this is basically the origin story of NASDAQ: the National Association of Securities Dealers believed (correctly) that they weren't getting good prices on existing stock exchanges, and computerizing a stock exchange had just become feasible, so they built an Automated Quotation system that initially just published prices to each other efficiently. Eventually it turned into an actual exchange.