As a pure keeper without accounting for batting, I'm not sure. To claim any one player as a clear-cut best as the article does is hyperbolic though. Healy was extremely good. Potentially the best I've seen, but Boucher also has an argument. And contenders from other eras, with Knott probably being the closest to a concensus pick.I dont know how you judge the best pure keeper overall tbh, and how you could decide if Healy was "better" than Knott or vice versa, but I do think Healy got forgotten because of how influential Gilchrist was with the bat immediately after Healy, and the fact that Gilchrist was a critical part of probably the strongest team ever assembled.
Gilchrists batting definitely made people forget Healy, because he broke the idea that a specialist keeper is good enough on top of his keeping records