You also proclaimed that one can "renew" a US visa in the country. You seem to be reading something that is not written and knowing something that is not true. Good luck with that!

are you referring to this? https://www.usa.gov/extend-visa

sorry, renew and extend don't really mean anything different to me, because the end result is the same: you get to stay longer. i don't see why they should be different and why that should matter.