Because it is written in perl and perl scripts like majordomo can
balloon to extremely large sizes on most platforms not just
Linux. Case in point: perl version of the ftp mirror script and
majordomo.
Real life non-Linux example:
No more than 2 majordomo's run at any one time on vger (Sun4/280 w/ 72
MB) since majordomo hogs so much f***in memory.
And don't talk to me about the mirror script ... :( (I did find a C
mirror that works very nicely with only 200 KB in-core. :) )