Odd, that's not been my experience in SF. I've only had one primary physician leave on me in 2018 (I'd been with him for 2 years, but only had visited once). My primary doc responds to messages within a day or two. Responses from the general care team are usually same-day. My primary physician is usually booked out a couple months, which is a bummer, but I can get next-day appointments with a PA or NP, and usually 2-3 days with an MD.
On top of that, it's been mostly easy to get prompt COVID testing when I've needed it, and for a while they even had 8-hour PCR test results.
For the most part I'm still very happy with the service, though this news about the Amazon acquisition is definitely making me question whether or not I will renew next year.