I think there is not enough light shone on these group of people but basically they have hijacked the whole process and are not technically skilled to understand good developers.
UK tech companies for example have been decimated because of this.
Someone has to do the work of pestering software developers on LinkedIn. If the external recruiters didn't do it, companies would just do it themselves.
That means you lose out on people who are actually good if you just talked to them for 30 minutes, but got screened out because they didn't remember CS algorithms off the top of their mind after 15 years in the industry delivering actual products.
Notice that you have written a trademark on your comment? Only the people that work on that place get to know, or to decide if there will be a scam or not. They get full control of what's happening.
That is something that should be avoided by employers as it for one increases the average compensation niveau faster than employee retention would and also constantly restarts opportunity costs as new employees take time to settle into their new roles. Yet, here we are and it is not only acceptable, but also standard procedure.