Agreed that some people can find it easier with explicit names - however some people find it easier with short meaningless names as it makes them focus on the abstraction rather than the naming. There is no right or wrong here. It all depends on the reader.

I even thought that this (hardness) was intended to emphasize the way it’s hard to spot problems in real codebase 😅

Should have still used them. It was harder to read this way.

The blog author is literally using de-facto standard for placeholder names.

• https://en.wikipedia.org/wiki/Foobar
• https://www.techopedia.com/definition/27996/frobnicate

The var names used by the author are perfectly fine. They don’t cause any issue, nor do they make things hard to read.