Why use time_historical_cutoff in steam api?

Question

Steam

So the question arose why this option is in the steam api. In English it is written, as I understand it, that when the "active trades" option is set, inactive trades will be received if their status is updated after the time specified in this option. I saw that in tradebots they set unixtime minus 30 seconds. What is the actual logic? Why should I receive inactive trades and how can they become active, why not just check only active trades? I understand that I missed some detail or misunderstood and because of this I can’t figure it out.
And if someone has already written a bot on node.js, explain the principle of node script initialization. Does it just do everything in order in the code? I worked with other languages, there is a certain initialization function that starts the code when the application / script starts.