I feel like the comment is a bit disingenuous, however; the complaint isn't "Zulip Business only includes push notifications" - rather, it's "the only thing I'd want out of paying for Zulip is push notifications." And indeed I would very happily pay for just notifications (which I assume costs a negligible fraction of the pricing) if it was a more reasonable price point (on the order of say, a dollar per user per month would still be a very healthy margin).
I suspect a lot of folks in a similar boat as me - sysadmins who pushed for Zulip as a Slack alternative at a small startup (with a nontrivial amount of convincing!) and are happy to deal with the hassles of self-hosting and don't ask for support. Having the price be exactly the same as a fully hosted solution, given the particular set of needs, then does feel like too much. I get that support is expensive, but having the option to not get support would be nice.
Of course, I totally get that you need to stay afloat, and it might be a short term way to get some money out of self-hosted customers. But it removes things that make Zulip appealing to someone who doesn't want support and would like to pay a more nominal fee for notifications (and certainly makes me less a lot likely to recommend it to someone setting up a new chat system, and I've done this a few times already).