Again only with TLV, yes those with carryons only can bypass the checkin counter, but from all the times Ive flown with TWA,PanAm,CO,UA,DL over the decades (and back when even carry-on only had to 1st hot the check-in counter) I think they would wait till T-? before off loading anyone, thats why at times there are announcements at the gate asking for x y and z to please come to the gate counter, yes sometimes its for something else but at times its to see if in fact they did show up. Taht said I believe the % of people going carry-on only is extremely small. I know a few folks who commute back and forth for work (mainly in the medical field) and they have bags going back to TLV but only a carry-on coming in and they make it a point to stop by the check-in counters to announce that they are there or the gate when it 1st opens.

At least UA has its game down pretty pat and know when they can start off loading some folks for VDBs. They really wait for the last possible min before doing anything and many a time I will see where some last min passengers are coming on sweating, either someone was VBDed or they were SBYs that cleared the very last second. But I dont recall a single time that anyone was IDBed at the gate usually if you got past the PP exit system youre good to go
As well as I cant recall a single time they came on board to solicit any Vols. this is both in NY and TLV

Things are done Overseas way different then Stateside, UA(CO) used to start @ $750 EWR-TLV while TLV-EWR was $500, and they always tried to get those who lived there so they wouldnt have to pony up for a hotel and taxis.