There are 2 reason: providing protection against Sybil attacks and rewarding nodes (i.e. the “servers”). From the whitepaper you linked:
This staking system provides a defence against Sybil attacks by limiting attackers based on the
amount of financial resources they have available. The staking system also achieves two other goals
which further reduce the likelihood of a Sybil attack.
Firstly, the need for attackers to buy or control Session Tokens to run Session Nodes creates a
market feedback loop which increases the cost of acquiring sufficient tokens to run large portions
of the network. That is, as the attacker buys or acquires more tokens and stakes them, removing
them from the circulating supply, the supply of the Session Token is decreased while the demand
from the attacker must be sustained. This causes the price of any remaining Session Tokens to
increase, creating an increasing price feedback loop which correlates with the scale of the attack.
The other advantage of a staked blockchain network is that Session Nodes earn rewards for the
work they do, paid as Session Tokens from the Session Node Staking Reward Pool. This system
makes Session distinct from altruistic networks like Tor and I2P and instead provides an incentive
linked directly with the performance of a Session Node.
E2E encryption it's not the only feature that matters. By the way, I am not promoting Telegram, I only mean that relying on US-centric infrastructure is bad because you can be disconnected away at any moment.
The difference is that Russia didn't have dozens of military bases in Ukraine, nor was its digital infrastructure provided by Russian companies, nor did its military rely extensively on Russian materials. Meanwhile, this is the case with Europe and the USA, and the sad reality is that Americans have so much leverage that they can do everything they want with Europe.
This "rule-based world" doesn't exist, and it never existed. An acceptable international order can only be guaranteed by an equilibrated balance of might between the different powers.
They use a standard Linux kernel with Android drivers trough libhybris. The proprietary UI and middleware is a mistake, I agree with that