Two things are involved
1. Either the exchange doesn't carry out any due deligence to ascertain if such projects are legit or
2. Their ieo fee is little to nothing
if the exchange was a top exchange they should attain their softcap at least
that makes a lot of sense, a cheap fee would be the main choice of the IE team to launch their tokens but that does not guarantee whether the token will be valuable on the exchange or not. and worse, the average ended badly, I experienced that.