I know packaging formats are a contentious issue on desktop Linux. They always have been, and likely always will be, but I’ve had a couple of drinks and have been out for the night at an excellent comedy show, so let me try and get my two cents down below 
Flatpak has at this point emerged as the defacto packaging standard of choice. It works extremely well out of the box across every mainstream distro… except for Ubuntu. Even downstreams of Ubuntu ship support for Flatpak (see e.g. Mint, Elementary and more)!
Snap to this day still has significant performance issues (like startup time). It has sandbox quirks, and other implementation-specific issues that are difficult or even impossible for third party developers to resolve.
As one of those third-party developers, working in a smallish team with limited resources, I’d much prefer to spend my time building an awesome app that users love than figuring out workarounds for one specific vendor’s packaging solution that only (sort of) works on only one specific distribution.
And then there’s the question of Canonical’s long-term commitment to Snaps. How long before they concede and support Flatpak like everybody else? See Upstart vs Systemd, Mir vs Wayland, Unity vs Gnome and many, many other examples of this Canonical-product-cycle for a sneak preview of where Snap is headed 
I hate that this is where we are at now. I developed native apps for Unity 8 on my Ubuntu-Touch-touting Nexus 4 back in the day (Snaps were called Clicks back then). I backed the Kickstarter for the Ubuntu Phone. I contributed in their mailing lists, weighed in on their weekly updates, and championed their vision for a modern desktop. I used Ubuntu exclusively on every PC I owned from 2008 to around 2017.
But Canonical/Ubuntu is no longer a contributor to the future of the Linux desktop if you ask me. They’re a distraction, impeding the health of the wider ecosystem by unnecessarily fracturing (and cynically, intentionally obstructing) a critical part of the developer story that’s otherwise been solved by better solutions, for profit and control.
That’s an extremely long-winded way to say I’m sorry, but we’re unlikely to ship a Snapped version of Plexamp any time soon. I hope I didn’t come across as rambling or crazy I understand the frustration with yet-another-packaging-format being the proposed solution here, but Flatpak works extremely well, has significant cross-distro investment, a successful and sustainable monetisation story, a full-time, paid team behind it, and it’s not controlled in full by one single, greedy company with a long history of commitment issues.
