imo treating it as a science does more to hurt the purpose of Marxism than it helps

marx and engel's project was originally conceived as a science in the true sense of the word, in the way we would consider physics or biology to be a science. But forcing abstract, universal laws (something which is essential to science) onto human civilization and development is extremely difficult, if not impossible to do in a productive way. More to the point, even within a single mode of production, the actual conditions on the ground at any given point will differ enormously, so any general doctrine will either lead you in the wrong direction or be abstracted to the point of being useless. Therefore, its more useful to think of Marxism as a methodology, not a science. Treating it this way keeps you in tune with the needs of the current place and time, and less focused on what should be happening according to abstract laws.

In addition, treating it as a science has the negative side of downplaying the moral force of socialism. No one I've met is socialist because they've been convinced by Marx's syllogism showing the inevitable decline of capitalism and rise of socialism. Rather, when you get down to it, people are socialists because they believe it to be the only way to create an ethical society. It is this moral force that represents the single greatest strength of any left politics, tbh. Treating Marxism as a science necessarily means you have to devalue that aspect.