Options commissions stopped falling in the mid 2010s

I've noticed that as time has gone on, the frantic pace of commission cutting has slowed. In fact, it doesn't look like the average commission per option contract has fallen for nearly 10 years. Early 2000s it was $5 plus a per contract, now it's just a contract fee – and that fee looks mostly unchanged at most brokers for a decade.

Any idea why this has happened? Why did commissions steadily decline until like 2017 and then stop?