Arianna Huffington on Thursday announced she would leave her position as editor-in-chief of the eponymous publication she cofounded 11 years ago to focus on her latest project -- Thrive Global, a lifestyle, health and wellness site. The reasons for her exit from The Huffington Post may be more complicated than that, however. Possible contributing factors include restiveness among staff over her leadership and judgment, reported clashes with AOL CEO Tim Armstrong, and concerns over Verizon's purchase of Yahoo last month.