Having no cap for Hatsu Levels will wreak havoc on the idea that Kurapika only received relatively small damage when he got hit by a BBI because of Emperor Time.
Let's assume that there were no caps for Hatsu Levels indeed.
So let's give Ubo a Reinforcement Hatsu Level of around... 100. He's been around long enough to get to this level. He's from Reinforcement, so he's getting 100% of Level 100.
Being a relative newcomer to Hatsu, Kurapika should only have reached around Level 15 for Reinforcement at best. This should be realistic since he has to worry more about his Materialization Levels. And, since he's from Materialization, he can only use up to 60% of Level 15.
So even with Emperor Time, he shouldn't have just received a fracture to the arm when he got hit by BBI. Emperor Time only brings him up to 100% usage of Reinforcement Level 15. Still a long way to go to match Ubo's Reinforcement Level 100.
If there were no caps, the case should have been that Kurapika's blocking arm would have been ripped entirely off, haggard-style, along with a handsome chunk of his torso. He would have most likely ended up like Worm, the thong-wearing Injuu, who got shredded into bits receiving a BBI from above ground. Doesn't matter if Kurapika was able to semi-dodge the BBI, since Level 100 is still too far from Level 15.
Emperor Time doesn't bring Kurapika's Reinforcement Level up. It just brings him to 100% of a Hatsu at its current Level. So scratch the idea of Emperor Time bringing him up to somewhere near Reinforcement Level 100. Also, Emperor Time was never said to give Kurapika a POP or AOP boost.
If the cap for Hatsus were as follows:
Level 10 for your innate Hatsu
Level 8 for the two Hatsus adjacent to your innate Hatsu
Level 6 for the two Hatsu below each of your adjacent Hatsus
Level 4 for the Hatsu opposite your innate Hatsu on the Hexagon
... then the damage received by Kurapika would make more sense, in respect to
- how Emperor Time works,
- the gap between Ubo and Kurapika's experience with nen and Hatsu, and
- ...the damage formula Kurapika's master scribbled.
So let's say we have caps.
Let's put Ubo at Reinforcement Level 10, the max. He can use 100% of it.
Let's put Kurapika at Reinforcement Level 6, the max for a Materialization user. He can use 60% of it.
Let's also consider their condition.
Ubo wasn't at 100% obviously, after fighting the Injuu and getting slightly tortured by Dartson and Kurapika. So let's put him at 90.
Kurapika seems to be at a good condition. Let's put him at around 100.
Let's also say that Kurapika used Emperor Time. He can now use 100% of Reinforcement Level 6.
Let's write the formula.
(90 AP + 100) - (100 DP + 60) =
(190) - (160) =
30
Kurapika would minimize the damage to around 30% of its original strength of the BBI. This damage would be a good reflection of the fracture that he actually got when BBI landed.
If there were no caps, and we use the earlier Reinforcement Level examples between Ubo and Kurapika, and use the damage formula, it would look like this:
(90 AP + 1000) - (100 DP + 150) =
(1090) - (250) =
840
840% damage would not just inflict a fracture but would leave Kurapika horribly disfigured and most likely dead, with or without Emperor Time...
Unless you're saying Togashi gave Kurapika a set of shiny plot armor.
Therefore it makes more sense that the Hatsu Levels cap at
Level 10 for your innate Hatsu
Level 8 for the two Hatsus adjacent to your innate Hatsu
Level 6 for the two Hatsu below each of your adjacent Hatsus
Level 4 for the Hatsu opposite your innate Hatsu on the Hexagon
...than having no caps for the Hatsu Levels at all.