While I do
a lot on the terminal, not everything is faster there.
Jumping between symbols in your IDE is not going to happen faster on the command line because it's a spatial operation. You've located the symbol visually, clicking it to jump to definition is far faster than keyboard-navigating to it, or even typing it.
Merging is better with a dedicated merge tool than a command line merge. I have to resolve conflicts one to three times per day and I couldn't imagine a non-visual merge interface for complex files where manual edits from both sides are necessary. Being able to see it all at once helps.
There is nothing quite as good as Xcode's instruments on the command line — providing easy to navigate visual representations of your performance and memory use, graphs and other metrics. Having the instruments panel on a second screen is incredibly useful, the extra screen real estate is of real value here. Having to keep switching on a single laptop display is a pain in the ass.
Obviously there are many tasks that cannot be easily sped up on the terminal, saving slices out from Photoshop (when your designer hasn't done it properly). And then getting the resulting assets into your pipeline. This stuff is benefited by extra screen space.
But the main benefit is being able to see more code at once. And it is especially helpful in large re-factoring operations or with extensive debugging / performance profiling. As I said, it depends on the type of work. I can code just fine on my laptop but I tend to prefer coding focused features, or fixing isolated bugs.
I find the previously mentioned profiling and architectural changes are better suited to large screens where more code / graphs / visual assets can be seen at once.
You simply can't do "all these things" in a terminal. You can do a hell of a lot, but sometimes you need visuals and sometimes you need space. When you can see more code you don't have to hold as much in your working memory, your eyes can flick back and forth over your code and it makes it easier to see the dependencies and realise what you need to change.