Don't worry, I won't contribute to negative internet points, this is a substantial response.
I agree no one should be religious about OSI's standards, but open source colloquially means "open for people to modify/fork/use" - I think the FOSS movement has created a similar colloquial definition even if FSF isn't the end all be all for free software. The differentiator "free as in freedom, not beer" is a great and uncontroversial litmus test for the community.
OSD 6 I think presents something similarly uncontroversial and closely tied to the colloquial definition of OSS (unlike other parts of their directive) which is "No Discrimination Against Fields of Endeavor" for licenses. It's not very open if one can't fork the project should their vision diverge, which is explicitly what both of Elastic's reasonably both paid and unpaid proprietary licenses will restrict - it keeps the software closed to their domain rather than fully open.
This is in contrast to open copyleft licenses which only require that you return contributions that you make to the codebase - something very comparable and that open source businesses have successfully worked with is dual licensing AGPL. With it I have no restrictions on how I use the software, but if I consider it a business need to begin running it, I have to be *open* about what I'm running.
It's not going against the broadly almost anyone's understanding of OSS to say "fork it, do whatever" or "fork it, just be open" - but it is going against most people's definition when it's "fork it, but you don't use it if you fall into a category that competes with our monopoly". Patent rights are an apt comparison - just because a patent is available for the public to view doesn't necessarily mean it's open for the public to expand on without paying a proprietor!
And what you say about the SSPL just being okay to run for your own purposes isn't true either - I've been advised by two lawyers at this point that section 13 I believe is so broad that it's viral enough to require you basically publish everything that you run in a stack because of how open they leave the language to interpretation, and their stipulation that it's "not that broad" in a FAQ does not supersede the language used in a license - Google attempted that defense early on in their battle with Oracle about how Java namespaces were previously advertised as open. It turns out the law prioritizes licenses over box stickers every time, and I don't think any business redistributing ES in any form can guarantee they're complying with the license (which redistributing in Elastic's SSPL's terms could be a logging facet for an application that's just backed by ES).
Anyways, I totally back companies making great software proprietary or closed, it pushes our industry forward - I just find it abhorrent the argument being out forward is that anyone can redefine "proprietary" if they're up against a massive company (even when they're a commercial and not so tiny business themselves) and especially if they're gaslighting the broader community about how they're doubling down on open without any irony or explanations about what the majority thinks open means in contrast.