From a platform development side, the reason bonuses shifted so aggressively over the last few years comes down to automated bonus hunting and risk management algorithms.
Back in the day, casinos ran legacy backend models that couldn't track real-time abusive betting patterns, multi-account scripts, or EV-positive wagering automated by bots. To survive the loss margins, operators had to implement tighter turnover limits, capped max cashouts, and strict automated KYC triggers directly into their platform engines.
Today, any decent platform relies on automated risk scoring modules built straight into the core software to handle promos. The days of 10x wagering no-deposit bonuses simply don't align with modern engine risk architecture unless a casino is willing to burn cash on fraud vectors.