This question already has an answer here:
Since my following quesiton is quite similar to this one Why is mining necessary for the Bitcoin network/system? I'm referring to the mentioned points of the accepted answer of this question that does in my opinion not answer the question at all or quite consice even though the answer is very long it just does not refer to the question. I'll explain why I make that statement.
Fairness - No massive energy consuming process is required (mining) ==> Does not answer the why mining
Stability - He also does not answer the why question he just assumes it is neccessary and explains the why a tranaction os not irreversible process in more detail. But he does not answer the why mining is required question, again he just assumes it is required and then explains a process built on that assumption.
Safety and security - At the last paragraph of this he comes up with a reason. The 51% attack. Is this the only reason that mining is required?
I'll also ask the question again: We could just hash the block without a nonce and it is also checksummed and the data integrity is ensured just as well as with a nonce. So why we need the nonce that requires such a massive energy consuming process? Is it only avoid avoid a 51% attack?