It's the solution mentioned in the article, lifting the RFID from the bypass cartridge to install it directly on the receiver circuit board. It allows you to keep using an "expired" filter rather than no filter at all.

But why would I filter potable tap water?

If it really tastes that bad in a particular region, central filters that you install where the pipe enters the house are cheap. Just make sure to get one that you can use generic filter media with (ie it's basically just a tube of some standard size).

People figure that they don't need to filter the water for showering, doing the dishes, flushing toilets, laundry, shaving, etc. Just drinking and ice. Both of those are at the fridge, so might as well put the filter there.

But, even with all that extra volume, is a central filter still cheaper? I'm thinking about a water softener soon, might as well throw that in.

If you do not have a well you most likely do not need a softener and it will just be another maintenance item and expense. If you have city water you would be better off with an activated charcoal filter or a RO unit.

My motivation for it is to eliminate all the calcium buildup on faucets, showerheads, etc. My water is very hard, and the constant cleaning I have to do is annoying. My cheapo TDS meter shows > 300ppm. I can't air dry my dishes without them coming out spotted and hazy.

As far as maintenance goes, my understanding is that the salt is dirt cheap. The new hassle I'm adding to avoid cleaning is lugging 40-lb. bags down to the basement, right?

I've never dealt with one before, so appreciate any insight there.

You have to back flush them and (at least for the two I have had in my life) tend to break a lot needing plumbing and electrical repair. Also the salt is corrosive so you need to be diligent as to where it is installed. The installers installed one of mine in the garage, near the air handler and I ended up replacing the air handler due to the location of the softener. I moved it outside while the handler was being replaced. They are of benefit in certain instances, such as yours and I would certainly buy another one if I where on a well again, but they come with their own set of headaches.

Even if you wanted to filter potable tap water, I am under the impression anything less than reverse osmosis is just a placebo.

Depends on what you want to filter. I used to have unsafe water from my well, and only reverse osmosis could make it safe. However safety isn't the only reason to filter water. If it is safe to drink but looks dirty a cheaper partical filter removes mud. If it is safe but tastes bad an activated charcoal filter will often be a cheap cure. If it is hard a water softener will fix that, but you want to drink the hard water instead of the softened water (though sodium content doesn't seem to be as much of a worry as it was 30 years ago. I'm note sure that it is science changing or not). I've also seen Iron filters.

Depending on the problem you need a different filter. Fridge filters only solve the simple problems where the water isn't too bad in the first place.

That would require modifying the plumbing system of the house, which would require to own the house or have the landlord's permission.

We're taught since childhood that one should only drink filtered or boiled water. It's not a matter of taste, it's a matter of pathogenic microorganisms. I would feel very uncomfortable drinking water directly from the plumbing without it going through a filter.

Most people in western countries drink straight tap water without filtering and certainly not boiling it.

Those things are absolutely not needed in countries with a modern water distribution network, they just bring added comfort.

I live in a large city in a major western country (Brazil), and I don't know anybody who drinks straight tap water without filtering. Every house or workplace has one or more water filters, normally connected to the plumbing (that is, there's a separate filtered tap for you to drink from), though there are also standalone filters (which are filled manually). Water for cooking is usually boiled (as a normal part of the cooking). We certainly learn in school that, to prevent diseases, water must be filtered or boiled (or bottled mineral water).

Brazil doesn't have effectively universally safe to drink tap water like the US and most western countries have.

Where do you live? That's certainly not the case everywhere. I drink water straight out of the well, and so does everyone else. It's normal to get a well tested when you buy a house, but unless you live near a swamp with a shallow well or something weird, you're unlikely to have any problems. There might be a pre-strain filter at the bottom of my well, but that's it.

City water definitely does not need to be filtered. Some people prefer the taste of filtered water, but there's no health reason requiring house filtration.

and then put a cheap inline filter on the water line going to the fridge. Problem solved.

An in-line filter is annoying though, as the replacement light on my non-DRM fridge is actually useful. It lights up when it's time to order a new filter. And then again when it's actually time to replace. And the filter isn't behind the fridge, it's right upfront.