Most of the old crypto gambling sites that had faucets in the past removed them because the gambler never made a deposit and was never going too. Many pioneer bitcoin dice sites like Primedice didn't have any ads to gain revenue, their revenue was the house edge and dice profits. So if somebody won big at a faucet deposit then it was a pure loss for them.
This actually wasn't a big issue in 2016 like I recall, but in 2017 there was just too many people who were abusing the system and they had no choice but to reduce the faucet, then lower it even further and finally just get rid of it all together. Because it was too much of a headache to keep having to freeze withdraws.
Ah yeah, the pure casino faucets were always the problematic ones especially for those who would go for 990x or even higher. I think some removed but others made it remain, but with certain conditions that count for abuse. I think the problem as you say became a big one in 2017 when waves of faucet abusers came online and sucked faucets and casino faucets dry..