> wtf even is a "default value"?

The article mentions the default value is a null, which would be the cue to run whatever computationally expensive op or query the db or hit the disk etc... that you would normally run if you had no cache to begin with.

> but screwdrivers make great hammers too

I don't know what your screwdrivers look like but that sounds like a rough time.

Generally you can use the back of a screwdriver like a hammer.

It works pretty well when you need to hit something with a solid object a couple times.