For me it all comes down to visual quality. Most HS games I have seen are noticeably worse looking than a comparable game made with Iray in Daz. This includes Carabdis's previous game. But he dramatically upgraded the visuals for Eternum to the point where it's more a matter of style choice than quality.DAZ might get you on Steam, but it costs more money to build an asset library, and with that comes financial risks.
Also, DAZ has even more UI problems than Studio Neo (The HS studio engine), is a bastard to work in, and with all of this you end up with girls that look like Barbies, and guys who look like Kens. I am of the same opinion as Caribdis, I don't like DAZ in any way. HS2 sucks, but DAZ is worse, more expensive, and produces a look I find ugly.
Edit: Oh, and to make matters worse, DAZ is so inefficient at rendering (because IRay is awful) that it requires additional beefy PCs for producing images and animations. With studio Neo, 4k renders (even with character skins modded into infinity), take no more than ten seconds, and 4k animations are only a few minutes per second (second edit: On an RTX 3070, it'll obviously be worse on lower end hardware, not that the 3070 is holding up very well right now).
As such, you can see why someone would prefer to "busk" in Studio Neo, than "sell" in DAZ with all the risks and expenses.
Ideally we would all work in blender, but the character and environment creation issue (i.e the time it takes - weeks instead of hours, per character - along with the expense) make this impossible until AI prompt modelling gets a little better. Which I am hoping happens in the two and a half years my Honey Select 2 project will take to complete.
So if he likes HS better and can produce visuals of the quality we see in Eternum I see no reason to change. I haven't used HS myself so I can't comment on how easy it is to use. I have used Daz and I find it reasonably easy to use except for animations which are a huge pain in the ass. My current system is really not up to par for rending complex scenes in Iray though. If HS is significantly less demanding from a hardware standpoint I could definitely see why people would prefer that.
The main draw for me to Daz is the availability of art assets made by someone else. I'm not an artist. Daz allows me to make good looking scenes without needing to be an artist. I can buy stuff that other people have made and use that in my scenes. I just need to practice posing and lighting and I'm good to go. I don't think Blender really has many options for that. You have to make everything yourself. If you're an artist that might be fine, although it's going to take you a lot longer than just buying some art assets and setting up a scene with already finished assets. I have no idea what the situation is like for art assets for HS.