I worked for an F500 that was still using Lotus Notes as of late 2018. It was my first job so I didn't know how old that system was, but people used it to build all sorts of complex applications like ticketing systems, time tracking, product design docs etc.

I guess Notion would be today's modern equivalent, will turn into tomorrow's legacy system.

I sometimes wonder if people have done any research on these types of workflow abstractions and come up with fundamental data structures to work with them.