Sometimes it comes of as an exaggeration when developers say that the industry moves very fast. To bring more perspective to it I'll be giving a personal scenario. Roughly six months ago, I was in a technical interview, the last technical question I was asked (which I answered correctly) is a question that would require a different answer today. Within less than six months the answer to a question can change from right to 'less' right.
The rapid pace of innovation requires that even industry experts review the basics every now and then. While some professionals can operate efficiently without keeping up with latest happenings in their industry, with tech you have to follow the news as it happens. This is majorly because when the average person accesses a digital platform with the latest features, that impeccable experience becomes the yardstick that will be used to evaluate the quality of other digital platforms.
At other times, security features are improved upon due to newly discovered threats. While not every new development in tech has to be embraced, the knowledge of said development helps facilitate informed conversations about the merits and demerits of said development in a bid to appraise the utility such a development provides. A developer is a lifelong learner. We study at least three times as much as we code.