Well, can't say you're wrong, but still, it doesn't actually mean that all affiliate programs are scamming people, affiliate marketing it's just another way of promoting and advertising the brand, could be broker, a dating website, etc.
I've been working for about 7 years as an affiliate for different sources, at the beginning I used my traffic on dating websites, primedate and some others, but for now I'm promoting only trading niche, cause I'm a trader myself (who is not trading these days lol) and besides my trading earnings, affiliate marketing for brokes also pays well.
I totally agree with you that some sketchy ass brokers would be scam almost 100%, but if the broker is on the market for a long time, then most probably they are not that scam. Try googling some brokers that are on the market at least for 2 years, it could be binary brokers, forex brokers and most probably, almost all of them do have affiliate programs. If you ask me, I'm 3 years into promoting binary platforms with Finministry aff network cause binary is the thing now and of course, crypto is the thing now as well, I mean, look at Bitcoin and how much it costs now, everyone would want to invest in it back into 2017 lol