I am kind of confused, why are modelmakers using machine threads for putting together 3d printed parts, when it seems a self-tapping thread would be a more logical choice? More, smaller threads does not mean it will hold together better. I have avoided several models just because they used machine threads.
Smaller threads are probably less likely to cause layers to come apart, you’re screwing in to the walls instead of biting in to them, if your threads are the same thickness as your walls you’re just asking for structural failure
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In addition to what Cypherous has already said:
Because machine screw are easier to loosen and screw back in again? So that assembly and disassembly are easier? Whereas self-tapping screws are designed to be tightened only once? Okay, maybe twice, but you shouldn’t do it too often. Depending on the application, either option can be advantageous.
People often want to modify, dismantle, or change something about the models.
Furthermore, self-tapping screws also need enough material to grip. This means that the hole must also have more than enough wall thickness. As I said, this does not mean that one is worse than the other or that one is illogical and the other is logical. It depends on the application.
But let’s be honest: if screws are stopping you from printing something, come on, give it a try. You can get a set like this for 5 to 10$. Actually, everyone should have a set of these screws next to their 3D printer. They’re so handy when you need one around the house, too. 
…or alternatively, a set that also includes the thread for 3D printing.
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I just have a set of M3 versions for my model scales, but i agree
I have the screws, both types, but I don’t think the machine thread screw solution is as robust as the model designer thinks. Like I said, I avoid models that call for machine thread screws where a self-tapping screw would be more appropriate, as for being able to take it apart and put it back together multiple times, if that is what the modeler is aiming for, then it should be designed with threaded inserts.
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I’m curious to know which models you’re referring to, especially if robustness is so important to you - also, given that a certain type of screw prevents you from printing completely. What kind of models have to meet such high standards? Functional parts? For what purpose?
So that means all decorative parts are already out of the question. Can you give me an example? I’m missing a bit of context here.
If you have such high demands on robustness, then the best choice is probably not to use screws at all, but to chemically weld the parts together. Or use a machine screw and a locknut.
Somewhere there’s still a missing piece of the puzzle as to what this is all about. As I mentioned, it might be helpful to provide an example of what you would print and what you wouldn’t.
Look, if you’d just said you don’t like certain screws, yeah, okay - but to completely stop you from printing something? That needs a bit more context. 
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This is one I was looking at today. [BaBo duo] AMS drawer stacker - Free 3D Print Model - MakerWorld
which, if I understand correctly, is calling for 40 screws that are machine thread and probably don’t get removed that often.
How about Plastite screws? Yes, there is such a thing. Designed for use in plastic.
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Okay, I can understand it in the context of the model: he just uses the screws offered by MakerWorld. Designers sometimes have to do that because otherwise the 3D model is less visible.
This is also indicated by the last icon.
Makerworld offers self-tapping screws, but not always in the lengths and shapes required. Especially with this model, the screws are countersunk, which MakerWorld does not offer as self-tapping to my knowledge. The designer’s vision was that the screws should not stick out, but be flush.
That’s why he has these badges, because he uses parts from MakerWorld, which in turn gives him more visibility.
Now let’s take another look at the first image: The first logo is an award for a prize in a competition. To do this, it is often necessary to use parts from the MakerWorld shop. I don’t mean this in a negative or positive way, because his success proves him right. We simply have to acknowledge that.
Now, to return to the subject:
So, if that’s your example of how not to do it… Phew! With 2,200 successful prints and prizes won. I don’t know if you’re going out on a limb there. Hey, everyone’s entitled to their opinion, go for it! But now you’re using a jugnerout of 3D design as a negative example? Holy moly! But I’m not going to deny you your opinion.
I would just like to point out that, as he is one of the top creators, he surely knows what he is doing… just something to think about.
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In my experience, anyway, machine screws can be threaded in/out of a print more times before the hole wrings out. Self tapping screws with their coarser threads chew up the hole a lot more each time they’re driven in and extracted.
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