I don’t hate flatpaks, but flatpaks require more disk space than the same apps from traditional repositories, and they only support a handful of the most common default themes. Since I only ever use older and slower computers, my disk space is limited, and I like to rice my desktop, I personally avoid them. But your use-case may differ.
Stable, in this context, just means “point release”. If you meant “doesn’t break”, that describes most rolling release distros.
…unless you’ve used KDE in the last month. Holy cow, just let me alt-tab into a fullscreen window without throwing a fit.