I do understand some of the points @DaltWisney has made regarding the way we install software in Ubuntu MATE. We have a different experience compared to other distros.
The Software Boutique "concept" aims to simplify this massive universe of Ubuntu/Debian packages by picking the best in class that covers a lot of computing needs, like a list of recommendations. Since it's neither a software centre or package manager, it can be a problem for less tech-savvy users (let's say, coming from Windows) who tried searching for "Zoom" (the video chat app) and it doesn't seem immediately obvious where to obtain it or how to install it.
The Linux way of obtaining software resolves around repositories, so at the moment, we need to educate about the "proper" tools (e.g. Synaptic, GNOME Software) to access the rest of the catalogue (which is via the More Software tab). Currently it's just one format -- Deb packages. Terminal is great if you know what you want - though this interface is better suited for a different audience, like power users and system admins.
Maybe next year I'll restart efforts on the so-called "Software Boutique 2.0" which will function as a K.I.S.S. software centre to install software without the end user needing to worry about any technical formats (Deb, Snap, Flatpak, etc). Power users, of course, can disable package methods they won't touch with a bargepole.
These competing universal formats (Snap, Flatpak) do add confusion and fragmentation. It doesn't help that Canonical (parent of Ubuntu) turned the chromium
deb into a snap, but that's just politics. (Easily heated too! )
In reality, a lot of Ubuntu derived distros (Linux Mint, elementaryOS and Zorin OS) share a vast majority of the same underlying packages - it's the out of the box experience and desktop environment that makes them unique. Snap/Flatpak are just alternate formats (with their pros and cons) as far as novices should be concerned -- it's like installing Amazon's Appstore alongside Google Play on Android.
It is interesting to read different user stories, but compromises may need to be made due to the diversity of the user base (... and I don't really know the target audience for Ubuntu MATE )