I don't think it's a dig against MLS, that's just a miles better professional life for Jack (providing he settled down, which he has) than he could ever make in England. Like it's better as a Sammarinese to play against Harry Kane (even if you do concede 10) than to not bother, assuming you had the ability to make the team in the first place.
Returning to the wider point, the scales are ridiculous. Statistically, if Wolves had a policy of only picking players who were born within the metropolitan borough of Wolverhampton, they'd have a nearly 10x better chance of forming a decent team than San Marino have. In reality it'd be an even better chance than that as you'd get a better youth grounding in football terms if you grew up here.