Sometimes their terms and conditions can be very ridiculous...When they advertise these bonuses they offer they don't add the necessary conditions and requirements, gamblers get disappointed after creating the bet account because they see that what was advertised wasn't really what they got.. it's hard to find casinos that give out bonuses without putting you through stress or doing a lot first to claim
I would say that casinos never plan to put newly registered gambler in stress, that is not what they try to achieve with bonuses. That is why welcome bonuses have lighter wagering requirement than promotional bonuses they offer. I am the person that recommend to grab welcome bonuses, as often they require only to share some private data (KYC, and if you plan to win big, then you would have to pass it anyway, keep that in mind), or only to verify email. Most common welcome bonus I saw in my local casinos are free spins with minimum bet size, zero wagering requirement but an obligatory KYC procedure.