This is also the dealbreaker for me, I use copy / paste from the scrollback buffer all the time. And also quick search through the scrollback buffer. I don't want to first pipe all the output to an editor or pager or something; that messes with the terminal colors, indentation, and it's an extra step, making the whole process slower and more tedious.

But I guess Zellij people don't use the keyboard so much for copy pasting. A lot of people just use the mouse.