Maybe the subset of japanese content I'm exposed to is biased, but personally I encounter doubled vowels (obaasan) more often than macron vowels (obāsan). The latter is explicitly "modified hepburn romanization". Even if the latter is more common in general, it's worth noting that the former is the original. The article seems to say that the former is weird and nonstandard, which afaik is completely false.

Also, the particles は を へ aren't always romanized the way they're pronounced; I can think of several places I've seen を written as wo despite being used as a particle.