The approach the author describes is batch processing, not time sharing. The whole point of time sharing was to allow users to work with the computer interactively rather than having to submit a job and wait for results.
notebooks are certainly interactive and Colab's purpose is to allow often low-powered clients to offload ML training/inference to a GNU-enabled server, so kind-of like time-shared systems of the old?
Speaking of mainframes... I ran across this video on the latest workflow for COBOL / CICS development on your IBM mainframe. You have the old 3270 emulation way yes, but then we move into 2010 technology: a custom version of Eclipse IDE that submits the jobs for you, then we move into modern times with Visual Studio Code integration (using something called Zowe CLI):
1. feature pipelines
2. batch inference pipelines