The Bounty campaign as a whole saw a decline in bounties at the end of 2018. Increased competition means each platform has to change its payouts to stay competitive. Each participant's analysis should be in place to gain a deeper understanding of how a campaign works and what you can earn from it.
In the era prior to 2018, we had ICO and they need the advertisements to raise money through crowd fundings. Almost all projects used to have a presence on bitcointalk.
Later, IDO, IEO came which don't need bounties for marketing and hence good projects do not focus on bounties these days.