I don't think that "consistent" always necessarily refers to pixel-perfect equality. When using this term in web dev, most would refer to browser standards as in spacing, layout, JS apis, availability of native elements etc. In this context, consistency is rather the opposite of negative. I don't think anyone really cares about how date picker looks on Firefox vs. on Chrome.

Maybe you are referring to Gtk/Qt vs. win32 etc. with their integrations in the operating system. I agree that they look and feel the best for their respective OS, but eventually require you maintain multiple unrelated codebases. It is understandable and necessary for this approach to die. A middle ground would be best, say, Qt support on all existing platforms. Or more likely, prettier browser defaults for standard elements like lists and tables, with browsers themselves respecting the underlying OS theme. Probably never gonna happen...