While I’m not quite sure what we’re talking about here in terms of platforms, I’ll mention a couple of personal and team server platforms that are subject to the Zombocom Problem and a couple that aren’t. WordPress, NextCloud, and OwnCloud try to be all you need and even though they have plugins they seem subject to the Zombocom problem, because stuff gets shoehorned into a particular app. On the other hand there is…
It started as a "blogging tool" and only that - it still is to some extent in 2024: it still has traces of "blogs" in its DBA, code, templating and so on.
It was successfull exactly because of that focus. As opposed to Joomla! and Drupal and many others that never even made it. WordPress gained a "plugin system" but later than most others and far more limited. In the beginning plugins were really to customize your blog - but it was still very much a blog.
When blogging wasn't that popular anymore - relatively, it pivoted into more of a brochureware CMS by leveraging the plugin system, but core was very much still a blog. I can't recall how many requests I had from customers to "remove this confusing blog-thing, we don't use that don't we". It could not be removed.
Then, after a while, it became the everything CMS. Slowly and rediculously clumsy. It still is. It's far worse at "being a webshop" than almost all dedicated webshop software one can choose instead. It's rediculously inadequate for anything close to "social media" - or user-generated content (due to its depenance on- and design of- the caching, mostly).
So, WP may be some "everything platform" by popularity and common use. But it's both bad at this and never predetermined to be that.