right now there is no oversubscribed validator on Kusama but a lot of validators on Polkadot are already oversubscribed, why stakers do not stake Kusama instead and insist nominating oversubscribes?
Kusama supports 1,000 active validators while Polkadot only supports 300 currently.
Kusama has 7,500 nominators.
Polkadot has 24,000 nominators.
This will naturally lead to more validators being oversubscribed on Polkadot.
As the network feels that the staking system is more stable and scalable, governance will increase these limits on Polkadot too.
Kusama is not as popular or high-profile as Polkadot, so it the latter attracts more nominators. According to the subscan.io stats,
- Polkadot ~950k holders
- Kusama ~246k holders
It is a different network, with different goals. I guess not all nominators want to experience chaos.
Without getting into "pricing", the ranking of the networks of various sites does generally what drives people toward the "blue chips", the numbers in accounts and active nominators show this.