Does it make sense to monitor distance v altitude: OH YES!
Sounds good in theory, but not a lot of time to continually be doing your 318.4 times table down final. Even with the table on the chart, it’s not practical to be continually monitoring it, especially in good weather. Speed, thrust and rate-of-descent (and the view out the window) would be the indicators something was amiss.
Looks like in this case the GS went for a ride and the autopilot obliged. The crew recovered and regrouped.