much of the gains of AVIF at lowest qualities come from features that don't exist in JPEG XL: wedges, large-support of the blurring filter, directional prediction
these features are non-helpful at normal photography bitrates and only complicate coding at bitrates above 1.5 or so
JPEG XL has similar approaches but its tools have a larger quality operating range
We evaluated these tools for JPEG XL and I rejected them due to them only helping at very lowest bit rates
there are many other ideas on how low quality JPEG XL images could be made, but it seems that it is more of a theoretical question since real use is always relatively high BPP: humans are 1000x more expensive than computers, so human experience can be prioritized over computer working harder for us.
I'm rather sympathetic to the argument of targeting actually used BPPs and think the benchmarks should reflect that (so "low" should be something like covering ~90% of actual images rather than some more arbitrary number), as it's another point of confusion counting against this great new format.
Though I miss your last point - how would human experience be harmed by allowing using low BPPs?
> only complicate coding at bitrates above 1.5 or so
these features could be disabled at higher bitrates as they're not helpful there?
