Every school if Buddhism is legitimate and valid. However different they appear to be. The difference becomes poignant and even important because people like us make it so. Due to our own personal preferences and experiences, we choose to accept or not accept something or someone. Many a times, it is very personal. However, when we put a group of people with similar preferences and experiences, they start to think that they are right and they begin to dictate what they perceive as absolute. But in truth, everyone is already flawed in their own perception. Because it is still governed by their own personal motives, desires, expectations and etc.
I have come to realise that the more people act in an in secure manner, the more personal interests they have in that object or issue. They need as much support and help as they can get so that what they want to believe in or achieve gets accomplished. Most people have personal interests in something or someone. Some even stand to gain on a personal level. Hence, they have a stronger desire or reason to maintain a certain view or issue or even rule/policy.
If following one path is considered Sectarian, then let's see how all schools of Tibetan Buddhism would react if HHDL asked every head of each school to abdicate having a head of their respective school. There would be no need for a Karmapa or a Sakya Trizin, etc. We do not need all these heads propagating over-looking one particular school then. We can immediately dissolve all of them and give all power to HHDL or the Prime Minister.
Truth is, we know it will not be done and cannot be done. There will be a serious chaos, if it indeed happen.
Each school stands as a method or path for people of the like minds to enter the spiritual journey. It is not the one path which presents the sectarian attitude and mindset. It is the people of a certain path which makes it sectarian. Again, it is politics. Games people play to bring about what they wish to accomplish for their own personal interests or the goals of their group.
For the rest of us, it is really up to all the different individuals to wake up and open their eyes to all this political games or not. And if we do open our eyes and minds, it is truly with the Dharma and not without.
The only way to end a conflict that enables everyone to benefit equally is the Dharma way.