That's my main problem really, I have Spotify, WhatsApp and a couple other closed-source applications on my smartphone that I need in order for said phone to be useful. If there are no ports or alternatives maintained on the Librem I'd just be buying a very expensive paperweight. And I don't think I'm a heavy app user compared to most of my friends who often have a couple social network apps, games etc...
Sibling comments mention that MS could probably make a profitable phone but they don't have the same objectives and I say that it's irrelevant. The problem is third parties and app supports. I need my phone to do more than calling and texting these days, I need decent driving directions, a multimedia player (ideally something that interfaces with Spotify, but I know that's asking for a lot), a chat application that can connect to WhatsApp (I won't convince all of my contacts to switch to Signal, Jabber or IRC) etc...
I need that stuff to be maintained and updated for at least a few years. And ideally after that I'd like to know that I can count on a Librem n+1 being available so that I won't have to change ecosystem once again.
I've bought a few open source/homebrew systems over the years, mainly handheld consoles to run emulators. It works but the software is often rather lackluster and very amateur looking. It's also generally maintained for a little while then the contributors move on to something else. It's fine for a toy emulator console, not so much for a smartphone.
The hardware is not the issue, the ecosystem is.