Internal in my opinion. Post 30 y/o specially, the dating scene for men becomes increasingly better (by market dynamics of offer/demand). But of course you need a minimum of soft skills to get more hits than misses in the dating game.

My take here is that people like the guy in the article lack the soft skills part but as he has grown up being self-aware of his height, probably blames all short-comings on that.

It would probably be simpler and more effective to do proper gym (better looks and more confidence) than this extreme and painful process.

I would like to hear someone who did the same procedure to hear if things actually got better now that they are taller.

Both really. I think taller men have an easier time getting a first date, but the second is more personality and how the guy acts.

The height factor is definitely a thing. Of course you can (or: have to) counterbalance it with other aspects but the sheer awareness that for some (substantial) population of young women you are disqualified form the start can be depressing.