That right there is the problem. a. Soccer does require more technical skill than a linesman. b. The QB position (which you seem to be conceding now) requires more technical skill than a linesman. Logically if you accept b. but not a. then that means you actually think soccer and a football linesman have equivalent technical skills. That's nonsense. Again, my nephew can walk on as a DE (not even a linesman) as a freshman with minimal experience. He could not do so for the soccer program at his school or on any (except maybe the Latino league team) of my son's teams.
It's ignored because it's irrelevant. That was already addressed. The money can be a function of other things such as body size, the impact the position makes, and athleticism. Football requires way more strength and a particular type of athleticism than does soccer. You see the converse in soccer BTW, as laid out in the soccernomics books. Goalkeeper is harder position to master. You need to be great in the modern game not just as a field player but you have all the additional skills of a goalkeeper on top of it. Goalkeepers are paid way less the strikers, less than a marquee playmaker, less than a centerback. Why? because the position is less valuable to the outcome....a goalkeeper can cost you the game, but he can't win it for you, and there's quite a bit of stuff that even the best goalkeeper won't have any impact on.
A far more interest (and open) question is where basketball fits on the skill hierarchy. My nephew's second sport is basketball. His school is lower ranked in basketball (only top 40) than football (top 20 SoCal). He has way more experience in basketball, having played rec ball until 12 and then a year and a half (because of COVID) club ball on what we would consider the equivalent of pre letter league. He has the nature height and physique for the forward role, which unlike guards, his school doesn't have a ton of. He was assigned the JV B team freshman year and this year dresses varsity but plays JV. Have fun.
