you make it sound like weight is the only reason people can’t find a shidduch…
When people ask someone’s size, i don’t answer. I’ve said on a previous thread, there are better ways of answering, especially since dresssize and appearance don’t often directly connect. Build and height play in too.
I do think any shadchan(te) who puts down a girl or boy for their size should be put in their place, and not be allowed to work in a sensitive area like shidduchim, for which they clearly lack tact and sensitivity.