What incentive do manufacturers have to release open firmware? Let's get serious, it's been 20+ years and desktop Linux usage isn't moving the needle or getting any of their attention.
IMHO it would be far better to put effort into change at a different level, like perhaps a broader push with right to repair legislation that expands it to include releasing firmware in addition to schematics, spare parts, etc. Change is going to have to come from a different source, you're just abusing users today for no benefit.
Everyone in the embedded space goes to kernel.org for WiFi stuff (firmware, regulatory info etc) regardless of which OS they're using. Being put at the top of the Wiki because you're "easy to work with" would be a massive advertisement.
By all means, the "free software community" should promote HW with free firmware, and giving the top spot on the kernel.org pages sounds like a good approach. And yeah, I spent a lot of time looking at wifi drivers when getting a wifi router. ath9k was the gold standard here with no blobs, and as a result was the favored platform for the wifi bufferbloat work. Unfortunately the follow-up ath10k needs a blob.
But I don't think punishing potential users who just want to get their laptop to work is particularly effective free software advocacy. Most likely the user has no clue what wifi chip their laptop has.
IMHO it would be far better to put effort into change at a different level, like perhaps a broader push with right to repair legislation that expands it to include releasing firmware in addition to schematics, spare parts, etc. Change is going to have to come from a different source, you're just abusing users today for no benefit.