This is a horrible thing to say! The great scholars Abu Yusuf and Muhammad ash-Shaybaani WERE INDEED mujtahids al-Mutlaq (the highest level of scholar, #1 above). And yes, they very well could have started their own madhhabs (and technically they did). However, you are not doing justice to their immense sincerity when you say that they followed Abu Hanifah "out of respect" for him. The truth is that they AGREED with Abu Hanifah. They didn't "follow him out of respect." Rather, in full sincerity, with the full conviction of their hearts, they actually agreed with the Usool of Abu Hanifah. And as a result, they were not following him at all. Rather, they were following their own ijtihad, which happened to be the same as Abu Hanifah's. But note that when they disagreed with Abu Hanifah, they did not make taqleed of him. Rather, they followed their own ijtihad, which is what every mujtahid MUST do.