I stopped using iTerm2 in favor of the default Terminal because iTerm2 has worse performance and latency [1], and I wasn't getting anything out of its additional features. I noticed an improvement going back to Terminal.app. YMMV of course; but if we're asking why Hyper is necessary, I'd like to ask the same question of iTerm2.

[1]: https://danluu.com/term-latency/