The blockquote element: HeydonWorks

Even before HTML5, was designated for longer quotations. Indeed, the term “block quotation” precedes the element and the concept of block-level HTML elements. The Chicago Manual Of Style recommends block quotations are over 100 words in length, for example. From this perspective, the element is not really applicable to pull quotes, since these typically constitute a brief phrase or remark. It doesn’t help to clarify matters that some of the examples from the specification itself are not, in fact, very long at all:

Source: The blockquote element: HeydonWorks