The problem herein is that what constitutes "spam" is subjective at best.
Examples:
1. The shouting of "YOOOOO" in the Gold Saucer when Yojimbo appears. Does this qualify? I'd say no, but I saw an argument yesterday evening in the Gold Saucer over this very thing.
2. A one-time shout advertising a nightclub event. Does this qualify? I'd say no, but plenty of other people despise any sort of nightclub advertisement.
3. Sound effect and text macros for PvP, along with constantly marking players on the team. Does this qualify? I'd say it can be annoying depending on how it's used, but others don't mind at all or even consider it necessary for coordination.
4. "Meowdy" and gigantic cat ASCII macros in party and raid chat. Does this qualify? I'd say yes, and everyone else should say yes, too
The point is, it's all quite up to interpretation. No great shock that GMs only intervene in truly extreme and obvious cases. "Spam" for some people is "whatever annoys me," and leaving it undefined is as intellectually absurd as Justice Potter Stewart's "I know it when I see it" definition of obscenity.
Furthermore, especially with 7.0, we can block words/phrases and blacklist anybody, so each of us will not have to see/read/encounter stuff that annoys us.