Infinite scrollback isn’t infinite. Infinite scrollback is a bug report saying “I played your game {all night | all week | all month} but the interpreter got so slow that I had to quit.”
(Quick search: https://intfiction.org/t/request-for-ideas-and-pre-introducing-gruelang/8936/16 ; github.com/garglk/garglk/issues/195 . I’m sure the problem has come up in other contexts.)
It’s true that the current limits in Quixe are conservative. It’s relying on your web browser, which has been heavily optimized for large amounts of text. I haven’t done any testing to find where it becomes a serious problem.