The design goal: always a defendant inside the EU
Article 8 does not simply name the manufacturer. It builds a chain, and the chain exists to solve one problem: an injured person in the Union should never be left with a valid claim and nobody reachable to bring it against.
That problem got worse as supply chains lengthened and as products began arriving from manufacturers with no European presence, sold through platforms, fulfilled from warehouses operated by third parties. Under the 1985 regime a claimant could end up chasing an entity in another jurisdiction with no assets nearby.
So the Directive works down a priority order, each rung catching what the one above it missed, and ends with a default that makes somebody liable if nobody else can be identified.
Where two or more operators are liable for the same damage, they are liable jointly and severally. The claimant may recover in full from any of them, and the operators sort out contribution between themselves afterwards.

