This is absurdly hyperbolic. Yes Jhin hits hard, but that is because he consolidates other dps stats into raw damage not because he is obtaining a ton of free stats. His crits deal less damage than usual to even out the crit -> ad and the attack speed -> ad ratio is just plain bad, just about every other champion is getting more dps from attack speed than Jhin is.
You can see with with some pretty simple math. Imagine a champion puts out 100 dps, specifically they are dealing 100 damage per shot and shoot once per second. If you give them 100% attack speed they now do 100 damage twice per second for 200 dps, or a 100% increase. If you give them 100% crit they now do 200 damage once per second (because crits deal double damage) and thus gain a 100% damage increase. As you can see 1% of either crit or attack speed increase a champions dps by 1%.
Now lets take Jhins stat modifications into account, he gets 25% of his attack speed as bonus ad and 40% of his crit as bonus ad. Also his crits only deal 50% more damage instead of 100%(It is listed as 25% less total crit damage, but 25% of 200% is 50%). Once again 100 damage per hit, one hit per second. Giving him 100% attack speed increases his damage by 25%, making it one shot for 125 every second or a 25% increase in dps. Increasing his crit by 100% gives him a 40% damage boost, so 140 damage per hit. It then of course crits for 50% more damage or a bonus 70 making the total 210 dps. Jhin wins this one by 10 dps and the total increase is 110%.
Now finally lets compare the two, 100% attack and 100% crit the super multiplicative damage increasers. And also lets remember that Jhin does get a passive 40% from his passive naturally at level 18.
100 dps + 100% crit is 200 damage per shot per second
200 dps + 100% attack speed is 200 damage per shot twice a second
Total = 400 dps
As you can see the true power of crit and attack speed is that they work on one another multiplicatively.
100 dps + [40% ad(passive) + 25%ad (from attack speed) + 40% ad (from crit)] = +105% ad
205 damage per shot per second + 50%(because it critically strikes)
307.5 dps
Jhin does not have that full benefit since crit and attack speed are both tossed into the same damage multiplication formula, he still gets a reduced multiplicative value because his crits hit for 50% additional damage but it is noticeably less. But of course in this case it would list the ADC as having 100 ad while Jhin would be listed at 205 so Jhin is obviously doing more damage right?
And we didn't even count for Jhin's reload times which late game come close to eating up half of hit time for attacks.
Now Jhin does still get compensated for attack speed and crit, but he does so by gaining defense through movement speed after crits. The point of this math is to show that Jhin actually has some of the worst scaling of any ADC in terms of damage output.
TLDR: Does Jhin do a lot of damage? Yes, but that is because he consolidates another ADC's damage into far less shots. In actual fact he does less raw dps than basically every ADC even before taking into account his reload times so claiming that late game he is gaining '8000-9000 gold value from his passive' is just ludicrous.