There's an entire subsection of the scriptwriting world that uses sequences when creating scripts. While this process was first implemented due to reel limitations (in the early days of film), it still has practical benefits in today's digital world.
I personally think that it is an excellent way to make a script seem less daunting when breaking it down into manageable portions.
The idea is that there are 8 (generally 15 minutes each) sequences in a feature length script. It can make a movie feel awfully blocky (see Aquaman -- watch it and skip to 15 minutes, 30 minutes, 45 minutes, 1 hour, etc.). Every 15 minutes or so is going to correspond to a sequence climax.
Part of the confusion, when talking about sequences and scenes is about having the instinct to know when a scene will fill the concept's idea/function without resorting to a sequence. In everyday speak: do I need to explore this idea more, or have I tried to wring too much out of this idea? Sometimes a scene is enough.
I also feel as though a sequence can be looked at entirely structurally, and in that way, it fulfills some important functions. However, in terms of story, a sequence also serves functions. It's this duality that makes the concept confusing.
Looking at Dramatica as an argument, I think it is fair to say that certain statements require less convincing than others. So, it is probably better to look at the sections of a novel, script, etc. intuitively when deciding how much of an argument needs to be made for a concept, but sequences can guide you in the beginning.
In regard to beats (especially as they are shown in Jim's Subtext app), I often notice that different beats provided within his app lend themselves (intuitively) to scenes, sequences, or -- even -- instantaneous character beats. In other words, they require the author to make a decision about how much time is needed to explore the beat in question. That, I suspect, is the art of writing (in acting, we often stay "within the choice lies the talent").
Another problem, you need to reconcile the differences in terminology when talking about Dramatica and other sources. Look at how people define essential vocabulary: beats, scenes, sequences, acts, etc. and then decide if those concepts translate directly to events, scenes, sequences, and acts within Dramatica.
In the end, I think it is completely reasonable to use a very rigid structure (3 Acts, 8 Sequences, 32 Scenes, etc.) when you are working on a first draft. But, then you can use your instinct or your talent to twist structure or manipulate it to make it work for your story.