I disagree. Split screen took some practice, but I sure as heck wouldn’t want to go back! I use split screen a _lot_ for reading & note taking, or writing and consulting reference material. (I use slide over when I need to consult or write notes less frequently.)

If you leave the Dock autopopulating recent and suggested apps, you launch an app, go “oh this would be good with that other app”, go launch that other app, then drag in app 1 to the screen from the Dock’s Recents section.