It says that because CIC is going to request the records on their own. However, since they want everyone to account for their time outside Canada, the best way of doing that is by looking at the CBSA entry records. Therefore, in my opinion, if you have travelled outside Canada in the last four years, you should request your records to see what they show before answering the question about absences. There is often an error in the entry records. It's better to know beforehand if this is the case, and not wait for CIC to catch it.