Because Canonical has forced telemetry and ads on their users, betraying everyone's trust? They built their business empire on distributing free CDs and financing local communities (on the condition that they ONLY promote/support Ubuntu)... All the hard, user-facing trust-building work was done by volunteers who've been definitely betrayed by this greedy corporation. We could also talk about questionable technical decisions:

- X11 model is broken, people are working on Wayland to replace it, let's write an entirely solution (Mir)

- GNOME2 is working too well and people are too happy with it, let's produce a desktop environment full of bugs at least for the next 4 years (Unity) instead of fixing bugs and performance issues in GNOME3

- Package managing is just a little too much reliable, what if we forced `apt` to install random snapcraft packages instead of the intended deb packages?

To get a bit of historical perspective, Ubuntu copied what worked really well with Mandrake/Mandriva: a user-friendly user interface. But they copied it to extinguish all alternatives, which mostly worked. Nowadays, Ubuntu is only good if you can get commercial support ($$$$) to fix everything they break.

Trusting two people with my secrets necessarily seems riskier than having to trust only one person with my secrets. Maybe the feeling is similar?