I agree that the fear of crime here is much higher than and disproportionate to the actual incidence. That said, if sat in Y I do routinely see the last few passengers struggle with their carry on, and tbf BA crew are normally very good about trying to figure out a solution, so the discussion is not totally academic, though it probably impacts less on most of those that post here than it does to the general population. The general population also tends to find occasional lounge use exciting, the mere presence of any free food impressive and cares little whether Groups 1, 2 and 3 are called together or separately.

Personally 90% of the time my carry on can be squeezed under the seat in front, so I don't need to worry about overhead space, although in practice I rarely have an actual issue. As for gate checking, I would say that it is on fewer than 1% of flights (up to 50 sh sectors a year) have I been approached for a gate check.