It seems like they, too, have no calendar application?
Google Calendar is the single most indispensable feature of the entire Google suite for me (apart from Mail, of course), so I can't see myself switching to something without, and yet Nextcloud continues being the seemingly only self-hosted alternative that has it (including the web interface: I don't want to have to run a second web browser like Thunderbird to edit calendar entries on my computer).
What is it about JS calendar shells that makes them so seemingly hard to implement? Even the big-name open source CalDAV servers like Baikal that flirt with corporate adoption never seem to implement them.
The post, at least, seems to have no word about a web interface, though? I'm aware of a number of CalDAV/CardDAV servers, but they all seem to be designed for a workflow where you only access the calendar from a mobile app. Conversely, standalone web calendars like the fullcalendar.io thing linked in a sibling post make no mention of any support for CalDAV or other ways to synchronise with phones and calendar apps.
It's the integration of both that makes Google (and, I guess, Nextcloud) useful: you can add an event on your computer (which is where most of the scheduling and planning happens), and then inspect and be alerted of it on your phone (which is with you when you are in a random location and need to be reminded of an event).
Even if there does exist a standalone JS calendar application that can sync with CalDAV, you would be left with an awkward setup when self-hosting, since now for no obvious reason you need to have two services on the same machine (the database and the frontend) that maintain a copy of the same state and need to sync with each other constantly.
There are dozens of open source Google calendar clones in JS; picking a random not-react example off of the front page of an npm search: https://fullcalendar.io/
I don't see anything about CalDAV, sync or mobile integration on that site, though. The thing that actually makes Google/Nextcloud calendars useful is that they enable a workflow where you schedule events on your computer (where most scheduling happens, at least for me) and then are reminded of it on your phone (which is with you when/where scheduled events actually happen).
I'd go a step farther and say that in a business environment, trying to schedule a meeting and seeing when invitees are available is the killer feature for workplace environments.
Google Calendar is the single most indispensable feature of the entire Google suite for me (apart from Mail, of course), so I can't see myself switching to something without, and yet Nextcloud continues being the seemingly only self-hosted alternative that has it (including the web interface: I don't want to have to run a second web browser like Thunderbird to edit calendar entries on my computer).
What is it about JS calendar shells that makes them so seemingly hard to implement? Even the big-name open source CalDAV servers like Baikal that flirt with corporate adoption never seem to implement them.