Software does not exist in a vacuum. You are probably right in thinking that story points should not matter to you, as a developer; but they do matter to external stakeholders.
Forecasting and management of expectations is necessary because software often has external real-world dependencies: available funding for a first release, marketing materials, hardware that can't be released without software, trade shows, developer conferences, yearly retail release parties, OEM partners, cyclic stable releases for enterprise customers who won't push software into production without extensive pre-testing, graphics adapters that can't be released without drivers, rockets that won't launch, cars that won't drive, etc.
All of these things require some degree of forecasting and appropriately-evolving management of expectations. Here's where we stand. Here's what we can commit to. Here's what we might deliver, but are willing to defer to a future release. Here are the (low value) items were under consideration that we will definitely defer to a future release, here are the features you will need to drop to get feature b in this release.
The purpose of story points is to help provide forecasting and management of expectations (with appropriately limited commitments) to stakeholders, on the understanding that forecasts are approximate.
Calibrated burndown of story points is pretty much the only basis on which forecasting and management of expectations can be done in an agile process. The key is to make sure that stakeholders understand the difference between forecasting and commitment, and to make sure your development team is appropriately protected by a healthy development process.
Whether the author's claim that you get better forecasts by just counting stories, instead of summing story points... color me skeptical. I do get that it prevents some obvious abuses of process, while enabling other that are just as bad. If somebody is using story points as a developer performance metric (which they shouldn't), there's nothing that prevents them from using completed stories as a developer performance metric (which they shouldn't). The corresponding abuse of process to combat that metric would be to hyper-decompose stories.