One reason I'm not on WordPress any more (myself) is the time requirements. Updates galore, breaks and fixes, tweaks, security, backups. A typical scenario would be a client who had hired a dev who installed a Themeforest theme which included every known plugin on the planet. A vulnerability would be discovered in a plugin and would be patched, but the theme dev would not update it, nor would any client get a notification of an update. Site hacked. Multiply times thousands and thousands. That type of infrastructure/setup started to get really, really tiresome after awhile, money or no.
So you can imagine my reaction when my current employer revamped their site and had a local firm charge them through the nose for a site which they threw together using WordPress and a ThemeForest theme. The devs were probably from fiverr (slight exaggeration). Now I put together how-to PDF files explaining to non-devs how to copy/paste raw HTML for every page edit, even though there is a massive page-builder plugin. The cut and paste is inside the page builder. Thirteen more days and I am out of here. That is what I keep telling myself.
I am still wrapping my mind around Kirby, but I do agree that for me, as a simple site owner (no more dev work for me - retired!) I value having certain functions in plugin form. I love drag and drop and automation. So I love the plugin installer. There, I said it.