the euphemism treadmill is a description of linguistic patterns, not a get out of rule free card
Using ableist language as insults is always bad, even if the words seem innocuous. Some may reference the "euphemism treadmill" to try to justify their behavior, but it's crucial to understand that the treadmill is merely a linguistic observation. It does not exist to normalize ableist behavior.
Idk man, a good chunk of these are just sorta not that associated with their origins anymore.
A lot of insults are historically demeaning towards certain groups (especially poor people).