A spam section is, by its very nature, a place where almost anything can be said.
Many, many topics could and would be made there every day.
What starts off as an innocent starting post can rapidly evolve into a total derailment.
With derailment comes flaming, and since the spam section is likely to be haunted by the less... eloquent and respectable members of the board, I daresay much would go unreported.
Moderators cannot be expected to trawl through this waste of hosting space daily to weed out these flame-fests, much less be expected to catch them before they escalate out of control.
To put it simply, a spam section is a waste of resources, both in terms of database space, and perhaps more importantly, moderator time and effort.