Procmail.log rotated by logrotate.conf directly

this may be bordering on trivia, but since I just spent some time figuring it out, I thought I would ask.

the module seems to set up logfile rotation for the file /var/log/procmail.log, but it appears it does so by appending text to the actual config file /etc/logrotate.conf.

I had assumed that, similar to many other packages, there would be a discrete file in /etc/logrotate.d/ … so I wanted to ask … what is the background for putting the lines

/var/log/procmail.log {
rotate 5

into the primary config file logrotate.conf instead of creating a file in logrotate.d/ ?

AND … will there be any ill effects if I adjust it myself?