I could not begin to speak for all, blossom but allow me to clarify my meaning to you. “Special snowflake” is generally used as a demeaning term to those who without any achievements yet, consider themself special. It also applies to those that might melt(figuratively) if they hear speech they disagree with. They are the kind that run away rather than hear speech they disagree with, or worse, will try to shut down someone they might disagree with rather than argue with superior facts. Or, (from wiki) “as being too emotionally vulnerable to cope with views that challenge their own.”
I have never heard the term “special snowflake” applied to someone with food allergies or wheelchair bound. I don’t know where you got that…