Every single one of those QBs except for Josh Allen you named was a much more effective player in college, against tougher competition, than Taysom Hill was.
Every single one of those players makes better decisions with the football and has shown a much higher football IQ at the quarterback position than Taysom Hill.
Lamar and Watson were first round picks for a reason. Because NFL scouts saw their production and their ability and said "that's an NFL quarterback". Hundreds of scouts watched Taysom Hill's extensive tape, and they decided that he was not an NFL quarterback to the tune of passing on him 255 times.
Him lighting it up in preseason and throwing one terribly underthrown ball to Deonte Harris in the playoffs doesn't change any of that. He has never in his life shown the ability to be an effective quarterback at a high level.
He has, as you mentioned, shown intangibles and the ability to be a great weapon. However that has absolutely nothing to do with playing QB.