There are still builds. People in games like WoW where you can change talents freely still have defined builds. They just have more flexibility to experiment and pick the build that fits them.
Again: I’m not saying there isn’t a good faith debate to be had about whether cost is valuable or not. I think the negatives outweigh the positives, you disagree. That’s fine. But there’s no world where ‘Experimentation is easier’ doesn’t lead to more different options. That’s just simple correlation.
One of the benefits of a ‘free choice’ system is that people find more choices that are fun to play as. One of the detriments, as you’ve pointed out, is that it potentially reduces replayability.