The first half of the first chapter of the Communist Manifesto is Marx being a total fanboy for capitalism and it's capacity for transforming the world.
Marx predicted that capitalist competition, which he expressed admiration for, would be too successful, and that people would just fail to reign it in and deal with the result.
There's a conceptually very simple fix to the crises Marx predicted if he's otherwise right:
Share more of the value, and spread labour around if automation comes to reduce the need for labour to the extent he predicted, where, to paraphrase, both overproduction and lack of work becomes common.
It doesn't take equality to prevent it, just enough adjustment to smooth out the crises enough to prevent escalation.
Marx took capitalists own predictions about the efficiency of capitalist competition at face value, and simply asked what will happen if capitalism eventually runs out of new markets to expand into (temporarily or permanently) and responds by driving down margins, and his prediction of eventual revolution is predicated on the assumption that society will fail to apply those very simple fixes.
Ironically, then, if capitalism survives, it might be because the competitive pressures are not as strong as Marx believed.
But I mean that's exactly the whole difference, right? Both Marx and others identified this pattern, Marx believes this ultimately will explode, others don't, so it makes sense that others would want to label it in a way that indicates their view that the pattern is "normal" and sustainable.
I'm not even saying Marx is wrong, but just because Marx thought something about something he noticed doesn't mean he's right. Others that came after him are allowed to come to different conclusions about the things he noticed.