Some percentage of telephone service, service chat etc. is stuff that could be easily found via the website, I know 98% of the time when I call it is just not possible to resolve through reading the documentation on someone's site (the last 2% it is, but the site sucks so much I don't want to try) and I'm sure it's the same for you and probably for most of HN, but having worked at a help and documentation service for a major telephony provider in Denmark I do know there are statistics that in fact show most of the stuff could be found on the site, people just don't want to take the time.

At that point the main problem for a service is to figure out when they are dealing with someone who could solve the problem through the website, and when they are dealing with someone whose problem is too complicated to be solved that way. Although it also seems like many people don't want to spend the money on doing that analysis and serving their customers, as you have pointed out.