But there are also some side projects where you just want to get your hands dirty with some different tech, if you do deliver something then you can showcase it on your portfolio. I know when the app store gold rush first started a lot of people did this as experience to get iOs dev jobs.
More often than not the skills I learn doing this kind of thing end up being very useful to me in the day job.
I'd like it if the side project was successful enough to justify all of that yak shaving, but I don't really expect it to be and I'm not that fussed when it isn't.
But if your primary goal is that your side project should become your day job then the article is pretty good advice. Leave your yak unshaven :)
99% of the time, if you want to go pragmatic, you should buy a ready-made solution (and then possibly adapt it to your use case). It's efficient (especially if you need the problem solved to make money) - but it's no fun.
Considering this is only a side project, you have a high likelihood of abandoning it out of boredom, lack of traction or simply burn out. However, if your side project is "interesting" to you because you are experimenting with various tech, you come back to it because it is fun and it will keep you motivated.
It is totally cool to build something to learn and throwaway, but why not build something to learn that might also generate some income in the future?