Well, at the time the article was written, cfront was still the C++ implementation, so this was a really long time ago. C++ was arguably as bad as the article said... then.

I'd say that C++ being fixed and becoming more popular took place in parallel. As it got used more, people saw more things that needed fixed, and as more things got fixed, it became more useful for more people.

Why did things get fixed nearly as fast as they got identified as problems? Because there was an arms race between Borland and Microsoft to have the best C++ compiler, primarily. That competition did wonders for the language (neglecting the horror of Microsoft's incompatible and ugly extensions...)