It's not so much about reward for node who produce blocks, but about proof that enough nodes on the network validated it aka solution to byzantine general problem. Otherwise , it's back to trusted nodes, centralized authority, etc, and the cost of operarion are then minimal.
I am not arguing that rewards to maintain consensus are unnecessary, just that inflation-based rewards are likely unnecessary.
I understand the reasoning for the necessity of block rewards, and do think they are necessary for PoW cryptocurrencies. But for PoS variants? I don't think that inflationary rewards are necessary.
Maybe PoS variants are not ideal as far as decentralization zealots are concerned. However, for 99% of the worlds population- they do not care about that kind of thing and PoS cryptocurrencies are sufficiently decentralized as is.
Yes POS is not permission less , unlike pow you need to have coin to participate, it's less anonymous, and a step away from the principle of decentralisation, permission less etc
But the thing is the important thing is not the reward, as i have seen even pos reward is a bit silly, because stake holder should be naturally incitated to keep the network functioning, only to keep the value of the coin, and the energy cost are marginal.
The whole point of reward and pow become useless in the context of trusted node.
Like with multichain and private chain, the security is not based on pow.
The energy cost of processing the transaction and producing the blocks in itself is marginal. Any regular user should have enough interest to keep the network working by itself, if it was only about processing tx.
The real cost is making sure all the network will accept the same block in permission less / decentralized manner. Basically to resolve orphan blocks and double spend, or cases where two different valid block are produced.
When you rely on trusted node, a common computer can process hundreds of tx / sec, and there is no need for PoW, only proof of identity of the trusted node to show the tx are valid and will be accepted by everyone.
And in the absolute, reward could be detached from coin emission, aka via tx fees or other.
If there was a way to determinstically determine in all the case which block or tx should be selected in case of conflict, there might not even be need for PoW at all.