There are plenty of reasons to doubt RDI:
An unsourced male DNA profile, unsourced fibers that were not linked to the home nor the residents, an unsourced human hair on the blanket the victim was wrapped in, animal hairs found on the victim & nowhere else in the home, two shoe prints not linked to the Ramseys, handwriting that wasn't matched to any Ramsey, rope, cord & duct tape not linked to the Ramseys, an unsourced backpack, a bat that did not belong to the Ramseys, a knife found on the counter in the basement that was not sourced to the Ramseys...
We're not talking about RDI.
We're talking about the stalker and the insider from your previous post.
How is it that a stalker was not spotted, but you theorize they got close enough to know about the dog, the staircase, the basement room, etc?