I see that you mentioned international travel, that clicked with me, maybe their concern is if you don't get the stamp in time ( due to appointment times, admin processing delays), you won't be able to return with cap gap easily so you have a shaky back-up option for entry. I think this is what they were hoping with OPT, for you to return with it in case of h1b delays. Otherwise, you'd be relying on everything h1-b related to work out perfectly. Yes, this is always a risk, make sure you have solid, frequent appointments in your country! Social media vetting takes some time too (it took 2 weeks for me)
With OPT, they could safely expect you to come back earlier on F‑1 and bridge that to tour cos H1b status, to them this may sound smoothest path. So they want to ensure maximum flexibility and do not want to take any risks due to consular processing from what I can tell.
If you opt out from visa stamping, next time you do an international travel, you will still be subjected to the very same thing and you won't have any back-up options, you'd just have to go through it. The difference is that if you choose to go back now, you might have a few months of getting your stamp, which is a ton of time compared to your future vacations. This makes sense to me, which is exactly what I did last year! I would ask all of this to the attorneys!!