If that was the case Oda could have explained the Gifter category with some of the hundreds of common soldiers who ate an artificial fruit, yet he chose to mix them with Headliners. I can group Buggy with Kaido if the criteria is showing devil fruit users, and since Oda has explicitly drawn many Headliners under the title of Gifters, then the logical assumption is that every Headliner who ate an artificial devil fruit is a Gifter because what defines such group is said consumption and not a power hierarchy; hence why Headliners were addressed as elite Gifters, which literally makes them Gifters whether elite or not; they are just higher within the same group.
It isn't rocket science, but you are forcing it as such while overcomplicating a simple thing. Every artificial user is a Gifter and some of them have the Headliner rank, hence why Holdem and company (66% of the whole group) were put in the Gifters category during a narration that is always speaking in present time. Plain and simple, you're just mixing up hierarchy based on strength and categories based on SMILE consumption, hence your flawed counter-argument regarding Buggy and Kaido.