BSDF is a term which describes a category of probabilistic reflection models, these being things which Blender's shaders are designed to implement. There are theoretically an infinite amount of BSDF shaders, and there are indeed multiple within Blender. Saying BSDF shader is like saying transportation car. It doesn't refer to any particular shader so surely what you read meant something else, or the person simply had no idea what they were writing about. Generally speaking, you should just stick the the principled shader, which the default when creating a new material anyways (and indeed you'll notice it says principled BSDF in the node's header).
All of the things which you describe wanting to do, can be done in Blender, but it seems that the software's goals and your own don't really align and that you don't even seem to realize it. Blender is a very general-purpose software and does not generally features tools for specific tasks like making rocks (such functionality is generally found in add-ons made by the community) because frankly, they wouldn't even be useful. Blender already offers countless ways to produce rocks by combining its individual features, and someone skilled with Blender could easily generate how ever many rocks they wanted, and with precise control. You could think about this by analogy: Would you reasonably expect Photoshop to have a tool specifically for drawing rocks? I don't think anyone reasonably would since it already can be easily done via some painting with its brushes, it could even be done entirely procedurally using filters, or by various other means. The software just isn't targeting people who want to make some rocks in 10 minutes; it's primarily targeting experienced 3D artists who probably spend hours and hours working on their art pieces.
The other software you mention however, are more specialized. They're either architectural or CAD software. It's a bit like comparing Microsoft Word to Photoshop and saying the the latter is bad because it's difficult to properly format paragraphs. It really just comes across as you having the wrong expectations from the software because you're not even comparing it to software which serves the same purposes.
I'd also like to point out that Blender actually has what is perhaps the cleanest and simplest UI of any general-purpose 3D application currently in existence. You can look at the competition if you don't believe me. They often get basic things wrong like having several (like 6+) rows of buttons right on top of each other. What I'm getting at is that when you complain about the UI being difficult and that "I guess that's free software for ya", it's really difficult to take your complaints seriously because the paid alternatives are actually substantially worse in this regard.
I'd also like to comment that as a graphics programmer, I actually find Blender to be extremely user-friendly and transparent. It's just a software which doesn't really baby you, and kind of assumes a familiarity with computer graphics, which I don't think is unreasonable given that' it's a computer graphics program. After all, it's not the brush's fault if someone don't know how to paint.
Either way, it just seems that this isn't really the software you were looking for.
