I think it's still pretty common if you play a lot of PC games, but it's likely much less so. There seem to be less and less games giving you out-of-the-box developer console access which over time will likely cause new video game players to not know about them as much.
The concept at least is well known by younger generations. There is an entire movie based on the Backrooms YouTube series coming out that is centered around the idea of "noclip."
