By general adoption. It's great that Librem serves you well, just like SfOS for me, but sadly we're a tiny minority. I think KaiOS has the third place in popularity.

GNU/Linux is also not successful by such definition. It doesn't make it worse than Windows.

Linux is succesful, it is a base for Android and billions of network devices.

Did you notice I had written GNU/Linux?

I've been using a Librem 5 as a daily driver for years and before that I used a PinePhone for several years. It can work if you're willing to adjust to live with it's constraints (but then also enjoy the benefits).