my take on flats:
--- a lot of experienced/knowledgeable players prefer them for all kinds of reasons (reasons which would be associated with the experience and knowledge of the player). if you know what you're doing and have chops = who cares what string you use? you deliver the goods, time after time...it's a non-issue.
--- a lot of players with less experience/knowledge prefer them because they 'don't hurt the fingers' so much and they produce less string noise... "squeaks." if you haven't practiced/played enough to have 'legitimate' chops (yet!) = you
really care about what the string is doing to your fingers and you are overly obsessed with noises you can't control (yet!).
also, related to flats: this one gets me every time --- "i just got my new/first fretless and i will be stringing it up with flats to save the fingerboard." or on a fretted "...to prevent fret wear."
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if you don't have adequate fingers/calluses/muscles --- on both hands! --- you aren't capable of doing any damage to fb's and frets ---
with any string type! it's all in your head...you don't yet 'have it' in your fingers!
in summary: some folks prefer flats. some folks are just avoiding rounds.
practicing a lot will actually give you more choices!
disclosure: i prefer rounds because i play fretless. i don't know what i'd prefer if i could handle a fretted.