The only difference I see is that when you're sub-ohming the vapour comes through much hotter so you need a wide drip so you don't burn your lips which forces you into DTL. Before I started vaping I was used to smoking roll ups where the tips got very thin and I carried that on to vaping and always used a flat drip tip MTL until I turned to sub-ohming because the flavour was such a massive improvement.
I guess for some people they think DTL is a bit of a credibility thing, but really who cares. As long as I've got a really nice vape and I get my nicotine fix I don't think it really matters. Just down to what people really prefer.