People understand that such "reverse hacking" can happen when their browser connects to any site (including all the indirect connections from dependent resources), right? Or when resolving any domain name? Or when even just pinging an IP?

The risk is far, far lower than browsing the internet. Unlike the massive surface of a browser and all the libraries and processes it is comprised of, the OpenSSH client is a tiny, with a singular purpose, contained in a small and very well-vetted codebase.

From the perspective of connecting to a foreign network service, the OpenSSH client is about the safest thing you can possibly use. Note the use of relative words here - not claiming it is 100% bug-free.

(The main caveat is that you can manually configure the client to do unsafe things, like writing a configuration by hand that enables X forwarding or agent forwarding by default for any host - but you can also actively disable sandboxing in your web browser or run everything as root, and we will never be able to stop you from actively making things insecure.)

There's also the terminal to consider, via terminal escape sequences.

Yes, but terminal escape sequences are a very, very small surface. It's just a few opcodes like "wipe screen", "switch to buffer B", "move to X,Y". All process output regardless of whether it is a terminal escape sequence or regular text just navigate and update the screen "cells", and in, say, alacritty this will be in boring, non-unsafe Rust.

For comparison, the surface exposed by your browser rendering this text controlled entirely by an adversary (me) is considerably greater as it also interacts with the style system, content reflow, javascript engine (even for non-javascript websites), etc.