it is rather the latter. Most major browser have pipelining deactivated per default. On OpenACS.org there are per day 10-100 pipelined requests out of 50k requests, and these requests are typically for embedded resources, where the "static" ns_sets are not used (on sites with aolserver or earlier versions of naviserver the pipelined requests are ignored).
But other sites might have different requirements and well maintained sites should strive for the newest release.
all the best from greece.
-gn
