For me it is a matter of credibility, Purism has none. After seeing all the
double speak by the main developer here in the past you couldn't pay me to
invest in their products, its simply not the way the head of a for-profit (or
any company head) should conduct himself. The lesser issue is that Purism
constantly conflates open source with libre as if they are exactly the same,
when they clearly are not. Many of the institutional backers don't have an
issue with using non-libre software themselves, users having easy access to
it, or it being added down stream.
I think there is a huge need for a transparent open source phone maker who is
clear about what is not free and does what it can to isolate those parts.
Important work could be done on such a system. A couple options already exist
that are far more credible than Purism's, I will be supporting those instead,
and will encourage others to do the same.
At this point, in order for Purism to even get a second look by me it would
take the FSF endorsing one of their projects or certifying one of their
products as libre. I don't see that ever happening.