But, in theory and according to the article, they should experience same effect. Just slower. When a (law-abiding) company finally has a strong reason to make some modification and keep it private, a proprietary replacement is coming. (Sometimes, as a "thin" fork of a permissive project, which then gets an engagement boost, reinforcing the point of the article)
Web engines are a huge practical example in favor of MPL/LGPL. They suggest that MPL/LGPL may indeed have the best survival characteristics.
Companies love proprietary browsers. If there were a good-enough permissive web engine, a proprietary fork would happen and "win", even if as "a set of patches" on top of a permissive base maintained by the community for free. Luckily, the creators of FOSS web engines seem to have understood that and chose MPL/LGPL. This goes against the article.
Companies love proprietary browsers. They will never contribute to a GPL web engine. That's why we don't have any good GPL web engines. This supports the article.
Companies love proprietary browsers. Microsoft was one of the first movers on the web. They had the chance to create a competitive proprietary web engine from scratch. It was popular for a few decades. But eventually Microsoft gave up and adopted Chromium instead. Presumably, to reduce maintenance costs. It doesn't seem like their proprietary engine gave them any competitive advantages that would be worth the cost. This supports the article.
So, the article is correct regarding GPL and proprietary, even (indirectly) predicting the continued absence of GPL web engines and the death of proprietary web engines. In 2015, when the article was written, IE was still bigger than Firefox and Safari on the desktop: https://en.wikipedia.org/wiki/Usage_share_of_web_browsers
But the article completely misses the huge success of MPL and LGPL. You are 100% correct.