Earlier quoted context omitted.
There's nothing wrong with monetization. There's just something wrong with making parts of the code proprietary. There'd be nothing wrong with monetizing by picking a copyleft license and selling exceptions, selling hosting, or selling support, for example.
Dual licensing (copyleft + commercial) has been a thing for a long time. Open Core is also a thing, and I think it's better than BSL because at least the core part is truly open.
As for Open Core, there is one case in which I think that's fine: when none of the proprietary parts would be useful at all in an otherwise 100% FOSS environment. For example, if Linux support were FOSS but all the Windows- and macOS-specific code were proprietary, or if a plugin to talk to Bugzilla were FOSS but a plugin to talk to JIRA were proprietary, I wouldn't see a problem.