Even I have the same doubt . When I checked with my office immigration team they told that once you fill out DS-160 you may not be allowed to travel back to US . Did anyone travelled in this situation by flight ?
Immigration is always confusing sometimes at some stages.
Technically it appears like we are applying but this is not like submitting DS160 and get your visa directly(like how we send our DS160 for the dropbox).
But its not the case. You need to appear for interview. If interview doesnt happen then there is no review of your application by the officer at all(or if interview get cancelled or if you miss the interview).
So thats why it will confuse some of the lawyers too since there is no clear cut clarity on all rules and on all stages. So its up to the interpretation of the individual/lawyer.
We commuters submit DS160 weeks/months ago(since we dont get appointments quickly or no walk-in) and do commute to US for weeks/months.
I dont think that the border gets notified just with the interview booking or by just submission of DS160(because interview might not even happen as we noted).