I mean, yes, this is correct. New Outlook, in terms of feature set and quality, is at best Public Beta status, and at this rate I don't think it will approach the functionality of Legacy Outlook for years, if ever. Literally the only thing it has going for it, in my view, is that it's snappy. I don't like any other thing about it; it's much less flexible than Legacy Outlook.
I've been advising all my clients who use Outlook for Mac to stay out of New Outlook until Legacy Outlook becomes no longer an option (and it will certainly remain an option until New Outlook offers on-premises Exchange support). Whatever its flaws, Legacy Outlook is a feature-complete and fully baked product, unlike New Outlook.
And yeah, Mac Mail is a perfectly viable and in many use cases superior alternative (and not without its own issues, but it is also a feature complete and fully baked product). It lacks some things I like in Mac Outlook like Advanced Search and Categories, but if you don't need those, I generally steer clients towards Mac Mail, with either Google, Exchange, or a specialty IMAP host behind it. (And I never steer anyone towards Outlook for iOS, even if they're using Outlook on the desktop.)