I would say that it is, and not just for the technical.
Putting Ubuntu on a laptop more than 6 months old is now trivial, and (given a non-exotic WiFi card) works fine. The problem is people being used certain to proprietary apps (Adobe Creative Suite/Cloud, Excel etc.).
The primary problem however, is that for the ordinary user, there’s little benefit to free software, assuming the machine is new enough to be performant, or the user is wealthy enough to replace it.
I’ll be interested to see if this changes when all the wonderful TPMs and for-your-own-good black-boxes start to get used for DRM.
I was mainly referring to putting Gentoo on a free-hardware* machine, so I don't think that would be recommendable to non-technical users for some time, but otherwise, yeah, agree with all your points.
Especially about buying new machines - Linux is very much a real benefit when hardware isn't considered disposable.
* which doesn't really exist in full, yet, but there's seems to be some initiatives gaining momentum.
I'm hopeful that this is at least becoming slowly more practical for some (more technical) people. Open hardware is the big blocker, but there at the very least seems to be much more mainstream popular interest in projects like System76's un-ME'd machines and similar initiatives then there was, say, 10 years ago. Baby steps.
As for building Linux from scratch, while I have quite happily used Gentoo for a while in the past, I think I'd echo some other commenters here on personally auditing every line of open source code: if you're not doing that, distrusting checksummed precompiled binaries is a somewhat odd distinction. The main differentiator is that the code is "auditable", not necessarily that it's actually been audited (see OpenSSH). If it's auditable, I consider that to be a not-absolute-but-still-significant improvement over closed systems.