It sounds like the person writing this article was forced to mention a "unique feature" for each website and they basically just wrote the same thing worded differently for the first three.

I think they mean that linking to Google Play won't lead to users downloading your app, not that merely including the link will slow down page load. The same is true of embeds, e.g. YouTube videos will fail to load, but the rest of the site won't be affected by that. The article's headline focusing on speed is probably just SEO.