I would think the astonishment would come from your usage. No, I have never heard of homely as a synonym of homey. I can understand how it could be. Ly usually means like when added to the end of a word, so like home, homely. It has been used to mean unattractive quite commonly and so would be impolite in certain circles as there is no need to embarrass or demean others, beauty is only skin deep. That saying. What is beyond beauty? Well, I guess warmth and love.