Maybe they would have hired Quality Engineers to test the complete site for UI and UX.
The reason might be anything. Besides that, if someone is good at bug bounty they can find bugs from any site and just report it to the owner.
If the site owner would be generous enough then they would reward that person anyway.
That is very true. Their proactiveness is the reason why there are less bugs in casino sites these days.
That must be the reason why the bug bounties have decreased so much over time.
In fact, this is good because as users we are getting a finished product rather than one with bugs which can compromise our privacy as well as funds.