> So unlike the title "co-chair" might imply, and unlike in many other organizations, IRTF co-chairs are little more than group secretaries.
The chair is far more than a "group secretary". As RFC 2014 section 5.3 states:
The Research Group Chair is concerned with making forward progress in
the areas under investigation, and has wide discretion in the conduct
of Research Group business. [...] The Chair has ultimate responsibility
for ensuring that a Research Group achieves forward progress.