This is an important step for testing, and I'm surprised that this is being spun as a move towards commercialization.
As of right now, waymo has only been doing what could metaphorically be called unit testing. That is, they test the cars behavior in very controlled but unrealistic environments, looking for very specific responses. The accident rate that they've incurred is likely ridiculously skewed: they've been driving in good weather, on meaningless routes (not chosen by destination, but by route features), at relatively safe times of day, at slow speeds, and they've been doing it extremely cautiously with engineers ready to take over in a moments notice.
This is exactly what they should have been doing, but politically it is misleading. Most human drivers, given those same constraints, would also do extremely well and way better than average. They've done well, but we have little basis for comparison with the average driver.
This is the first step towards integration testing. They get to see how the cars behavior integrates together across various scenarios that are much closer to real life. They are driving on actual routes that real people travel on...routes that aren't chosen in order to test a specific behavior.
Accident rates are going to go up. That's a good thing...its a move towards the things humans find more difficult too. We should, however, expect slowing progress to level 4 autonomy. This is typical of system capability growth; exponential in the beginning, asymptotic near the end. People that are rushing this are out of line; akin to immediate commercializations of lab rat successes. Give them time.