The royals are like that, always.
They would award new lands to people who achieved something great, like becoming a Tier-8 powerhouse. These would be the best benefits they give out, at least that's what they say.
It was actually a trap for the powerhouses.
The kingdom doesn't like to let go of such powerhouses.
The kingdom is nothing but an ant before empires like Redthorne or Frost Empires. The resources that flowed through the empires in a month would be much more than what flowed through the kingdom in the entire year.
There is no way that the kingdom would be helpful for Tier-8 professionals. If they want to grow further, they have to leave the kingdom to places like the empire.
It means that the kingdom would lose a lot of fighting power, the top fighting power nonetheless. This is something that they can't let happen, no matter what.
The best way to not let them leave was to tie them with the kingdom.