It’s strapless, it has to be tight enough to hold itself up.
I do think the percentage of boobage showing is probably proportional to a much smaller endowed prom attendee who got to show her 40% without being embarrassed. Still think it’s a shame someone started all this hoopla.
My mom was an excellent seamstress, trust me, that dress does not fit and if it has to be that tight to have support for the strapless part it is also very poorly made.