How rude is it to hijack a thread?

I am aware this is considered rude by most jellies.

I think I have an idea why. Especially in general or as pertains to a personal question, the emphasis should be placed on the actual question or possible strategem and advice for optimum resolution.

However in relation to social questions: politics, economy, humanity one question can trigger many all of which are relevant to the larger topic.

Is this really offensive? Or say people are getting too serious interject some humor take it down a notch. Breathe, laugh, and resume.

Too me it feels organic like a tree the trunk is the first question or topic and in a productive thread all responses stem from the first but grow further away from the source.

I think this is especially true of questions that have a definite answer. Something that can be quickly answered by someone with a particular expertise or knowledge.

I usually find all information and opinions in relation to my topic of interest to me. So I am happy to let the thread go wild. And fallaciously assume others are just as thrilled. So I need help recovering from hijacking ways.

Where do you stand, and why.