There is mildly disruptive and then there is there is really disruptive ...
No you wouldn't even the roughest schools in the country would not need to loose anything like that many. It is very much a minority that cause a significant enough disruption to efect the learning of others, but don't let that stop your daily mail style ranting!
So I say again; where do you draw the line? It doesn't take much to disrupt a class (what is a "minority"? what are "mildly", or "really", or "significant enough disruption"?) when class sizes are large and teachers stressed. Do you only remove the children who are clearly mentally incapable of doing the work, or do you remove the extremely smart ones who feel so under-challenged by a purely academic class which holds no interest for them that they become disruptive through boredom?
And stop throwing comments like "daily mail style ranting" around. It just makes you seem like you have to label people who don't agree with you.
Exams are a perfectly good method of assessing academic things
No, exams are a good method of assessing one thing: can you regurgitate enough information about a specific topic to answer a small number of specific questions on that topic, in a fixed amount of time under stressful circumstances. Sometimes that requirement matches the requirement of a given academic course. Usually, I would suggest, it doesn't.
Suggest a better alternative, continuous classroom assesment has been shown to be inconsistent at best especially when the teacher has a vested interest in the results.
Sadly there are few provably "better" alternatives which don't require a lot more class time. One possible method would be coursework, managed with University-style supervisions or tutorials so that the teacher is always aware of the student's progress and so can understand the student's thought processes and appreciate their level of understanding of the subject. I'm aware that the resources simply don't exist to use such a method in most teaching environments.
The argument that exams are not a good method of assessment is one that is used when talking about those who are deemed to be academically weak...
This simply isn't true. There are some incredibly dense people who thrive on cramming for, and passing exams, and some incredibly smart people who simply cannot handle the format, or the pressure, of an exam situation, and so under-perform. These, and others, are the argument against exams. And those are only arguments which apply to subjects whose material actually suits an examination!