What are the CD/CI benefits of using Scratch org?
I am trying to know the benefits of using Scratch.org for CI/CD. But the Salesforce document shows that the scratch org is the disposable and source-driven deployment of Salesforce code and metadata, designed for applying automation and programmers. But it also says that projects and scratch orgs can be applied by an individual. That is why there is no chance of merging or witness file conflicts.
[Reference](https://developer.salesforce.com/docs/atlas.en-us.sfdx_dev.meta/sfdx_dev/sfdx_dev_push_md_to_scratch_org.htm)
I think the Scratch org allows developers to perform pre-validation to avoid errors before the final deployment. Since asking 20 developers to push touched metadata for major releases into a Scratch org is not recommended, I think we should leverage the CI/CD tools for automating the deployment process against Sandbox org.
Using Scratch.org and populating it from the version control system via sfdx force: source: push, you can get the assurance that everything you need is present in the version control. You can provide the developer with a baseline for developing, helping the delta work simply and with ease so it can manage and bring back the version control by using the sfdx force:source:pull command.
You can run each commit and merge if you prefer to run the pipeline against can be run parallelly. But it would be best to focus on the branching and merge strategy against the version control system offers without risking shared org. It means that the CI/CD process is simple and responds faster.