Without Ofsted, teachers would have more time, more freedom and lower stress-levels – and they'd be able to concentrate more on actually educating their students.
Ofsted reports are largely meaningless. I've seen terrible schools get a glowing Ofsted report – all it means is that they've jumped through the hoops and produced the paperwork Ofsted need to cover their own backs. It says little or nothing about how well-educated the students are.
Teachers concentrate so much on impressing Ofsted – and following the Ofsted-supplied formula for what they consider to be "good" teaching, that there is little room for flexibility and innovation. Many of the very best teachers are mavericks who don't follow the rules – and many of them have already been driven out of the profession as it is.