Was IPR necessary?

(Apologies if you've already seen this post, I wasn't sure it posted the first time) I have a question about some IPR I recently had done. Back in January 2020, I went to an orthodontist for an Invisalign consultation regarding a 4 mm overjet of my two front teeth and minor spacing between them and the teeth next to them, among other issues I was not as concerned with. The orthodontist looked at my teeth for a few minutes, did some measurements, then said I'd need aligners on both arches. He then looked again and said he thought he could get it done with just an aligner on the top arch, coming to this conclusion without any scan of the teeth. This past October, I went to another orthodontist who said I'd probably need IPR on some bottom teeth to fix the overjet. He was surprised the other orthodontist thought he could do this with only a single arch treatment. After scanning my teeth, I did indeed need IPR, so I went with that. I understand a double arch treatment is generally recommended to avoid bite issues, but I wish I got a third opinion, so I'm asking here after the fact. Here is my ClearCorrect plan from my teeth scan so you can how they looked before and a picture of my teeth from 2017 (not smiling). https://dr.clearcorrect.com/treatment-plan/public/CB5BA342-FDB0-400D-9813-9B359FEF222E/8DD8E0BF-F006-4E85-B9A4-36DE086768A7. The second orthodontist said the plan would "align both arches and relieve any crowding while correcting the rotations and angulation of the teeth. The general shapes of both arches are improved and your lower mid-line will be slightly shifted back towards the center. We will need to perform IPR in the lower arch to improve the overjet and overbite." Attached is an old 2017 pic of my teeth. I completely understand if no one can have an informed opinion considering you never saw my teeth in person. Thanks!