You know many mixer campaigns in the past have max weekly post cap is 50 posts and even the most successful campaign ChipMixer have about 50 participants with that 50-weekly post cap. There is no spam problem with ChipMixer because they only hired most quality, best posters in the forum.
Compare the difference in image of users enrolled in these two campaigns: CM signatures were a sign of good posts. Most users with Stake signature are just spamming. Stake literally doesn't care, so I can only guess spamming is profitable for them.