Shared albums are not "instead of," but "in addition to." Pictures there are copied from your Library with lower resolution and without their metadata intact. They're meant for sharing with strangers, I guess. It's cool that, even though they are new pictures (and thus have new dates,) they don't count against your iCloud storage. You can see this:
Create or join shared albums in Photos on Mac - Apple Support
You can sort albums with a right-click:

If you have lots of albums, it really helps to organize them into folders. I have some event albums in month foldrers, those and other events in Year folder, and Year folders inside of Decade folders-- so hundreds of albums can take up only a few folders that fit in one screen in the Sidebar. I also have albums that are not events, but general types of things that are in separate folders.
You can see this:
Organizing photos with Folders & Albums - Apple Community
In Tahoe, but not in High Sierra, it's cool that "File>Show in Album" is provided to show the album and folder structure for a picture.