"With" originally meant something closer to "against," whereas "mid" was closer to "with" in today's English.
Over time, "with" changed meanings, we gained the word "against" and "mid" survives in fossil form in words like "midwife."
> if an outfit is described as “mid”, the implication is that the outfit is bad and the person should not be wearing it.
I'd say most people on the Internet have been conditioned since childhood to deliver and expect "white lies" on such topics. The actual mid-tier/average outfit is indicated by nonspecific reactions such as "you look great!". Saying "this looks average" is pretty much an insult. Greatness, or extreme badness, are communicated by expending extra effort on description, delivery or acts surrounding it. Similar phenomenon applies to pretty much anything involving descriptions of individuals or their choices.
In the extreme, you get the supposed[0] German way of doing employee references, where a reference is never in any way negative, but if it looks ordinary, like "Person X is never late", it is to be mentally prefixed with "Literally the only good thing we can say about them is that...".
This kind of heavily biased distribution of scales seems to be a wider thing in general. Obvious examples are all kinds of star ratings on-line: in e-commerce, in app stores, delivery services, restaurants, etc.: 5 stars out of 5 is "good", 4 stars is "meh", anything below is strictly negative.
From my own life, I remember one pre-internet case: school grades. On a scale of 1-5, with 6 being awarded for extraordinary achievements, the actual scale - as perceived by teachers, parents and students - was: 1-3 = various shades of bad; 4 = meh/average; 5 = what parents expect you should be getting by default; 6 = what parents expect you to get if you show minimum effort.
--
[0] - Something I've read about multiple times on HN.
(Asking as a Norwegian, since “ved” is “by” or “beside”)