General auditions attract far more kpop stans than talent. Many of the best have not even considered joining a kpop group, and would never join a general audition for one (especially for people outside Korea).
Given how visuals are basically a must for new kpop groups, would it save the companies time and money recruiting straight from the best source of visuals: influencers (particularity singers/dancers) and international modeling agencies? This seems better than finding attractive people on the street and asking them to audition (I have heard a lot of stories like that).
The obvious benefit is that many of the most beautiful people in the world are likely already an influencer or model, so if you want the best that's where you should go. They have proven their potential to some extent, have experience in front of cameras, probably already have followers, and are easy to find and contact.
At the end of the process you only want about 4-9 people in the group, so why not aim for the best from the beginning and let the kpop training system do the rest?
Teddy is already doing this. The only known trainee for his next group is a famous model with 4M insta followers, Ella Gross: