Can somebody elaborate on what the last paragraph means? If I have a limit of count per page and I know which page I am based on URL I can always generate a pre

Can somebody elaborate on what the last paragraph means? If I have a limit of count per page and I know which page I am based on URL I can always generate a prev/next page link. I guess it is pointing out that limit/offset needs be used in such a case. How did reddit do it in terms or pagination? Such a large website wouldn’t survive on limit/offset.