Differences in the features of Microsoft Office suite of applications has been an issue since the dawn of time. This is nothing new and no amount of pressure is going to solve it. If if makes you feel any better/worse, the "New Outlook" interface is dumbed down on Windows as well, missing a large list of features that are/were in what Microsoft now calls the "Classic" version. This is true on the current default Mac and Windows versions.
I personally stopped using the desktop versions of Outlook (Windows and Mac) many years ago for this reason and have only used the web version of Outlook for 365 since. I love the fact that I can sit at any computer, on any desktop OS, and have exactly the same user interface and experience when using any modern browser. I will admit that there are a few features that sometimes are dumbed down in the web version but in some cases the experience is actually superior to the desktop versions. Clearly this only works well for me because in may case I have suitable storage in my 365 account to host all of my mail. The only time I ever use the desktop version of Outlook any more is to create occasional backup copies of my mailbox as Mac Outlook export format, as a Windows .PST file, and as .MBOX files (yes, I am serious about having great backups for cloud-hosted data).
I have not used a POP account in over a decade so am not sure why Outlook may have issues with that. If possible I would recommend moving away from POP as support is not likely to improve in the future. If you want to use POP accounts then Thunderbird client may be a better choice that Outlook.
