You would think it would be easier for them to just reject me.
A waitlist, while effectively VERY similar to a rejection, does not mean the same thing in the eyes of the admissions office.
A rejection is the final destination to that applicant’s journey. For whatever reason- their essays weren’t up to par, their SAT score was too low, they got a mediocre LOR, they just didn’t impress them enough- that student would not be offered admission.
A waitlist offer means that they liked you. They did not want to outright reject you. HOWEVER, they also did not want to accept you. You were strong, but not quite strong enough. So, in case not everyone they say yes to says yes back, they want to have the opportunity to offer you admission further down the road.
It’s also related to business for them- the college wants to have a waitlist to ensure they fill the seats in their class, and so they don’t lose money if they don’t get a good yield.
If you’d rather be rejected, you do have the option to turn down the spot on the waitlist which would have the same effect as a rejection in that the admission process with that college will be over and you will not be attending.