Making some really nice speakers isn't super difficult if you follow a plan like Directiva. The problem is that there is no free lunch... the best designs incorporate the best drivers, which tend to cost a lot. Purifi-based designs tend to measure well and sound good, but it's around $1K a pair just to get in the door with those builds. Certainly not a bad value for money if you compare specs and measurements, but there's no such thing as "The $100 speaker that beats Genelec" or anything like that, regardless of how good the instructions are.
This is why DIY isn't more popular IMO.
If you have $1000s to spend on speakers that reach the state of the art, you'll probably just do that, instead of spending $1000s on drivers so you can spend 100 hours building speakers that reach SOTA. If those 100 hours aren't fun for you, it's just a difficult way to get a good set of speakers. I have what I would call an unhealthy inclination toward DIY for the sake of it, so DIY speakers appeal to me... but if you're not the type to build furniture just because you think you can, I would not necessarily pursue DIY speakers either.
If you only have $100s to spend on speakers, it's very hard to beat a nice set of bookshelves from JBL or ELAC, Revel, Genelec, etc. by doing it DIY. The prices of DIY drivers are not low enough to close the gap on mass-produced, quality mid-tier speakers.