Quite. First you have to establish that the child was actually abducted then you theorise about how it was accomplished.
The fact that Madeleine had disappeared and Kate's statement of how she found the shutters and windows open is evidence of abduction.
If you don't accept evidence from family members, then why was Sarah Payne immediately considered to have been abducted. She disappeared and only a family member claimed to have seen anything.
The same goes for Ben Needham - he disappeared and we only have his family's word for what happened.
But in your eyes - as there was no independent witness evidence of abduction - it was not possible to be established. That is not how the police work IMO.
Establishing the credibility of witnesses is vital in cases where no physical evidence is found - and IMO that is what the police did in all the above cases - including the McCann case.
It's clear to me that the police have fully satisfied themselves that both Kerry Needham and her family - and the McCanns - are all credible witnesses. This has enabled them to rule them out as suspects and it follows therefore that removal by a stranger is the only other viablle alternative. And they are the experts.
If you want to ignore the experts - that's up to you.