Or, it could be them adding some pieces to WC that weren't in their toolbox (whether they were ever in the art or not isn't terribly relevant - they were never in their version of the art). Might that change their approach to WC? Sure. But you're saying that if they make certain changes, you no longer accept what they are doing as WC. I'd argue WC is only a name, and applies to whatever people define it as. If their base (what they built upon) is WC, then what they do can legitimately be referred to as WC, or at least a derivative of WC. At some point, it probably needs an identifier to avoid confusion. "Wing Chun Boxing" is a reasonably descriptive moniker for a WC base with WB tools and tactics integrated. For the purist, it's not fully WC. For many others, it's as WC in their minds as what they do. Who's right? I'm not sure "right" is all that important here.Problem is the concepts are missing and needing to be made up for by resorting to other styles, and in the end, these guys end up basically just doing Western Boxing while still calling it Wing Chun, or "Wing Chun Boxing".
That's not progressing the art. That's just tacking the name onto something completely different so that it can appear as if Wing Chun isn't as useless as it has been acknowledged to be.