Here's the DIR logic from the source:
Baker's Dozen for not using a Dive Computer By Jarrod Jablonski
1) Dive computers tend to induce significant levels of diver dependance,
eliminating the awareness so common and essential to all diving but
particularly obvious when diving tables
2) Dive computers do not allow proper planning as divers can't properly
"study" the impact of various mixture and decompression choices.
3) Dive computers are of very limited educational benefit as they do not
induce questioning, or proper planning discussions as can be found with
tables and most particularly with deco programs
4) Dive computer programmers often play games with computational process
so that they can take insulate themselves from the risk of taking
largely square profile data and utilizing it on a multilevel dive. These
games tend to result in odd and often ridiculous levels of conservation.
5) Dive computers are expensive and in some cases leave divers with
limited resources carrying equipment that is of far less benefit than
other equipment that may have been purchased.
6) Dive computers significantly limit the likelihood that divers will
track their residual nitrogen groups.
7) Dive computers do not allow for Helium diving in any formats but the
bulkiest and most questionable format.
8) Dive computers will often generate longer decompressions than could
be figured by an astute, well educated diver with experience.
9) Dive computers often create confusion by giving the user to much
useless information, sometimes even obscuring depth and time in favor of
blinking CNS and/or deco limitations.
10) Dive computers can become very difficult to properly if a deco stop
has been violated. Some computers lock up completely while others just
beep or generate erroneous and distracting information. Divers using
mixed gasses are likely to often violate computer profiles.
11) Dive computers do not allow for the educated diver to properly
modify their decompression to account for advancing knowledge such as
the use of deeper stops in a decompression profile.
12) Dive computers do not offer divers as much flexibility in the
generation of profiles with varying conservation. For example the right
mix would allow 100 min at 60 vs 60 at 60 but I might prefer to do one
or the other and indeed might like a compromise. Computers confuse this
issue by not providing divers with the proper information.
13) Dive computers users often ignore table proficiency and therefore do
not learn tables properly. When confronted with a situation where they
can't dive the computer (failure, loss, travel etc) these divers are at
a serious handicap.
