Maybe it is a dumb question
We know that there are numerous layer2 scalability solutions.
Why we still need to promote sharding on layer1 of Eth2.0?
Or it means if Layer1 still need to enough scalability to suit any Layer2 solution?
Because most of these layer 2 scalability solutions come with serious security and/or usability tradeoffs. See https://vitalik.ca/general/2019/06/12/plasma_vs_sharding.html and https://vitalik.ca/general/2019/08/28/hybrid_layer_2.html for some background.
Does it mean that Eth2.0 try to solve all of things(e.g.security Decentralization scalability) on Layer1 if eth 2.0 could do ?
Yes, eth2 tries to achieve all three at the same time.
What you said makes me connect OSI model in my mind. Even the internet can’t satisfy all the things on the same layer. I am curious about why you choose to do so. Or is there some important things that need to be done on the layer2.
For example, It is well known that zk-zk rollup is the new layer2 and grabs your attention. What it can do and layer1 can’t do well at the same time?