Maybe because they need to do that every day with variations and automating away the monotonous chore is one of the main points of writing code.

> I saw my colleagues again and again implementing basic algorithms such as rolling median, or finding a maximum.

Emphasis mine so I will go with no regarding your explanation. It’s obvious the discussion was about one shot plotting from the start. The whole Go vs Python discussion for graphing doesn’t make sense in the context of automation.

Because Excel sucks at plotting, especially if you have non-trivial amounts of data.