It depends on use cases.

I have multiple projects running in different locations/timezones - so I don't often need to have an agent running on a pc elsewhere - but just being able to smartly use herdr (also using rex) to set up a persistent service on those computers removes all the friction which used to exist with ssh keys and other things.

So I could do all these things before, tools like herdr make it easier, smoother.

Now tmux and ssh keys enabled all this before. So in a sense, nothing new here. but its a bit like dropbox - i used rsync back then, dropbox just made it easier to setup sharing and use without thinking.

My current anecdotal example: if you're building cross-platform native apps, you need to run agents on macOS and Windows, because xcodebuild only runs on macOS and the Windows SDK is only available on Windows.

Because they use resources (tests, etc) and once you have a few running it impacts you.