I have a macbook and iMac. How can I continue working on my pictures from notebook to desktop? W/o export/import catalog many times? Some like a Lightroom Mobile?
Lightroom is designed as a single-computer, single-user system. Syncing files between multiple computers requires you do jump though some hoops.
My recommendation and the easiest solution is to put your catalog and images on an external drive and move the drive from computer to computer as needed.
Copying the catalog from computer to computer over your local network would be the next option.
"Export as catalog" and "import from catalog" would be the third option.
Why the restriction of no export/import of catalogs? Those functions were specifically designed for this purpose...