AutoFill is a feature provided by CRA, which is supported by Turbotax products.
AutoFill requires secure access to your tax information, which is protected at CRA for the sake of your privacy by only allowing you to obtain the tax information, through your My Account registration.
AutoFill is therefore both private and optional for CRA taxpayers, and there is no way that any other party can access your information unless they hav obtained specific permission from you, and filed this consent with CRA for example on form T1013. Any party preparing taxes on your behalf needs to do this.
Since CRA doesn't have all your credit information, and may not have all necessary T-slips at the time you choose to do your tax return, then it is necessary to collect that information from the taxpayer. The questionnaire is simply a means of automating the process where a human tax preparer asks profiling questions.
The profiling step is intended to reduce the tax preparation time by preventing the user from seeing a large number of unneeded screens. Most all tax software uses this approach.
CRA puts the onus on the taxpayer to perform self-assessment in reporting income and credits, and advises you to check all AutoFill data for accuracy and completeness. This is good advice!