Well, I had never scrubbed in because my home program was very strict with the COVID policy, and I had never sutured before because I took your "advice" and unintentionally had my first externship be a hands-on one at the start of my clinical D3 year. If anything, I suggest people to extern at an observation-only externship at first so they can get a feel for the hospital life.
Additionally, dude, the attendings are in academia -- they LOVE to teach. And if they don't want to teach a student how to scrub, then they will tell their resident to. And if the residents have a problem teaching a clueless dental student the absolute basics on how to scrub in, then that really isn't a program I want to train at (unless they were in a time crunch or something, of course).
The argument is hands-on as your first externship, not top program first. I agree with you that you should save your top program for closer to the application cycle and not your very first one. I was rebutting your statement on the hands-on one being first, when I actually think an observation-only externship might be better as the very first. Regardless, it really doesn't matter. Just show up on time, be willing to learn, and act interested in everything while on the minimal sleep you will have that week.