No no no, that's bullshit. A properly designed font isn't just the outlines, it's the outlines + spacing. Type designers spend almost as many hours perfecting the built in kerning as they do creating the outlines themselves, because the space is integral to the font as a whole.

Yes there are times, especially with display type, that you want to adjust the kerning between a few pairs of glyphs, but to say to "never trust a font to provide your kerning" suggests to me that you use a lot of poorly designed free fonts rather than professionally realized typefaces from reputable font foundries.

I would love it if the browsers would all support the built in kerning in a font by default, with a way to override it manually.

In most cases its actually the opposite.

If you are using quality fonts, as you should be, you will only need to adjust the kerning in very rare cases. The type designers are the ones who have to concern themselves heavily with the font kerning. Which is why font design software, such as fontlab or glyphs, have an insane amount of kerning related functionality, whereas the kerning provided by something like, say, photoshop or indesign, will do what you need it to--which is make minimal adjustments in corner cases.