You are missing the subtle difference between some and all.
You can quite comfortably take good points from any theory and adapt them, whether they are Marxist, Hayekian or Keynesian. You don't have to take all the theory as word. I appreciate Marx made some great points, but he was also not a fan of Socialism, I am a Socialist. You can take part of the Nicomachean Ethics without being a lover of Aristotle and so on, because the world is a different place to when these great tracts were written. If you seriously believe that the Labour Party advocate the violent overthrowing of the state by the proletariat then I think you really have to look into why Labour is a Democratic Socialist party, the emphasis on Democratic. I am of the opinion others are not as is the lefts want that it was Lenin who was the greatest advocate of violent overthrowing of the state, he was a revolutionary. I have not seen or heard any Labour MP describe themselves as a Leninist. If you read Orwell at length who in my opinion is one of the greatest writers ever, he is vehemently against authoritarian orthodoxy, he probably has had as much influence on the left as anyone.
Your use of the word Marxist is just the same as others using the word Nazi on another thread. Its an attempt to smear, its shallow and unthinking and basically shows a lack of imagination. I seriously do not believe that the right are Nazis, just as I don't believe the left are Marxists, its lazy to think that. What happens on both sides is the evolution of the old thinking into new views based on the old. Like I said, would you call everybody who advocates calling for free education for children a Marxist? No you would not in the same way I would not call all those advocating for cuts in immigration Nazi's.
Seriously this is how low and debased politics in this country has become, there are no grown ups anymore, just people throwing out lazy smears and stupid innuendo which adds absolutely nothing to any serious debate. If you start from the view people are extremists then those extremes widen and a vacuum is created and consensus becomes impossible. That is where we are at now with the Brexit impasse. The other danger is the more that unorthodox thinking is promoted, the more orthodox it becomes and you get the creep of acceptance and the standardisation of the thinking as the norms.