Chocobo Racing should give Tomestones

[Astrahime]

Those are just assumptions or do you have data on that? Maybe giving regular tomestones would help? Why not test it?

I have data, it's called the queue. At R-240/300 you're basically guaranteed to run into one other person doing Chocobo Racing, whether it's to farm MGP or wins or level their Chocobo.
Verminion pops even less than Mahjong does, which is saying something. Especially given that you only need 2 people for Verminion.

Can you stop trying to argue the point that a single specific Gold Saucer Duty is worthy of dropping tomestones rather than all of the other ones?
You're in the Gold Saucer to get the Gold Saucer currency. If you want the Combat currency, go do Combat content.