I've always thought such unnecessary padding was primarily to increase search engine ranking (more topic keywords & more length being generally favored). In today's world, almost no one is incentivized to answer your question as concisely as possible. Usually, quite the opposite because satisfying queries faster tends to reduce their metrics (page views, time-on-site, etc).

A secondary contributing cause is that many people aren't very good at structuring explanations. For example, the old rule of thumb that you usually won't miss anything important if you skip the first third of most YouTube how-to videos existed before the algorithm disfavored very short videos (and post-TikTok that's all changed too).