I'm sorry to break it to you, but they neither give it away for nothing, nor do they give it to anyone. That's not my definition of "freely".
[1] https://www.kauffman.org/reports/the-anatomy-of-an-entrepren...
I can easily melt ice into water, but for most solids, that's very hard for me to do. It still makes sense for me to categorize ice as a solid though, rather than saying that there's no reason to categorize it separately from other liquids.
Their original complaint wasn't about defining these groups (one can debate that classes are supposed to be more rigid than this), but the "collapse of all indenties" into these two buckets - which material dialectics calls for. It's a criticism specific towards Marxism and its notion of "no war but class war".