Sounds like it :) I’ve been very happy with Mail.app since MacOS 10.0. My use has always been with my employer’s IMAP servers, and my own cryus (and eventually) dovecot self-hosted IMAP servers.
Mail.app is what NeXT used internally, and Apple uses to this day AFAIK. Steve Jobs historically paid a lot of attention to it and wasn’t shy about weighing in on any changes.
Most of the complaints that I’ve heard about it seemed to stem from poor IMAP servers (e.g. Gmail), but it sounds like your knowledge in the space would be a lot more detailed and recent than mine, so I would be very interested in your thoughts.
Gmail does indeed _intentionally_ provide poor IMAP service. But the long and short of it is that Apple Mail simply isn't a first-class product. It's an afterthought.
Mail.app is what NeXT used internally, and Apple uses to this day AFAIK. Steve Jobs historically paid a lot of attention to it and wasn’t shy about weighing in on any changes.
Most of the complaints that I’ve heard about it seemed to stem from poor IMAP servers (e.g. Gmail), but it sounds like your knowledge in the space would be a lot more detailed and recent than mine, so I would be very interested in your thoughts.