Casino platforms that offer high bonuses are only the attraction for casinos to appear superior to rival casinos, but you are right that the bonuses offered cannot be owned because they have to meet difficult rules, so that in the end gamblers get bored because bonuses can only be used for betting and not added for fiat withdrawals. So it's better to use the top casinos for a chance to win from promotions than from the "fake" bonuses on offer.
Fake bonuses? I haven't heard of it but maybe that means the bonus is hard to come by because some conditions have to be met.
Bonuses are an attraction for gamblers in any casino, but they may not automatically increase site traffic if the site is not as good as expected. Some beautiful women sent messages on whatsapp and offered a lot of bonuses from certain casinos, this is more often I ignore than directly register and get the bonus.