I believe that this has more has to do with it being built into almost all CMS's than it being a conscious decision.

I remember creating a couple of years back a simple script where you input a subdomain or a top level domain and it would try loading the most common feed locations (like /rss, /feed etc.) and returns the location of the feed if it gets 200 as a response. All I had to do was to check for like 10 different locations (think: one or two for every major CMS) and it worked in like 98% of the time.