In the post-mainframe golden age, before UNIX and C came to screw everything up, people were using highly interactive programming environments with REPLs, system-wide debuggers, ability to work directly on running processes, etc. I think having access to such tools does not diminish your ability to think (I'm judging by my experience with those tools which somewhat survived in the Lisp world). But the issue with distracting OS seems more real. Back in the 70s, they didn't have a task bar with IM, music player and web browser waiting for you there. It was you and your dev environment.