I can't speak for OP, but I suggest that they're highlighting the fact that instead of a broad base of large companies in a variety of industries, Canada's big company wealth is highlighted in a narrow set of verticals.

This means that corporate investment might be more slanted towards that areas, and it also means a narrower set of potential customers for a given application.

I know what you mean, and I'm sure that's what the OP intended, but these "verticals" are energy, minerals and money. Literally everyone needs these things, which is the definition of a horizontal market.

Anyway, as a Canadian computer scientist I'd be very happy to see knowledge industry grow here.

I think the point is to draw attention to the nature of Canada's economy, not to discount it entirely.