i don't understand how that works since they wouldn't be able to determine gross/net proceeds or really any of the information required by the 1099-B. i'm guessing the reddit rep was misinformed or there was otherwise some miscommunication or misunderstanding.
you can see who must file a 1099-B here under "specific instructions": https://www.irs.gov/pub/irs-pdf/i1099b.pdf
i don't see how someone only buying/withdrawing BTC fits any of those conditions, or why square would spend time/money sending 1099s when they aren't required.
not showing basis just means the burden is on you to track and report all your gains and losses, instead of relying on what square reports.