The main reason not to compare Jackson to Lobb is that Lobb is not the standard to measure blokes of Jackson's draft pick/talent/hype/cost should be measured against.At Jackson’s age, Lobb had played 2 games. Hardly fair to compare.
If Jackson only got to Lobb's current level, that would be massively underwhelming.
If he's generational, compare him to Goodes, Stynes or some other massive tall dude who was athletic.